diff --git a/goldens/public-api/angular_devkit/build_angular/src/index.md b/goldens/public-api/angular_devkit/build_angular/src/index.md
index 1565e61b9b6a..30a86d584b93 100644
--- a/goldens/public-api/angular_devkit/build_angular/src/index.md
+++ b/goldens/public-api/angular_devkit/build_angular/src/index.md
@@ -43,7 +43,8 @@ export interface BrowserBuilderOptions {
     deployUrl?: string;
     extractLicenses?: boolean;
     fileReplacements?: FileReplacement[];
-    i18nMissingTranslation?: I18NMissingTranslation;
+    i18nDuplicateTranslation?: I18NTranslation;
+    i18nMissingTranslation?: I18NTranslation;
     index: IndexUnion;
     inlineStyleLanguage?: InlineStyleLanguage;
     localize?: Localize;
@@ -259,7 +260,8 @@ export interface ServerBuilderOptions {
     externalDependencies?: string[];
     extractLicenses?: boolean;
     fileReplacements?: FileReplacement_3[];
-    i18nMissingTranslation?: I18NMissingTranslation_2;
+    i18nDuplicateTranslation?: I18NTranslation_2;
+    i18nMissingTranslation?: I18NTranslation_2;
     inlineStyleLanguage?: InlineStyleLanguage_3;
     localize?: Localize_2;
     main: string;
diff --git a/packages/angular_devkit/build_angular/src/builders/browser/schema.json b/packages/angular_devkit/build_angular/src/builders/browser/schema.json
index 54bbdd52bade..4e15f47faa9f 100644
--- a/packages/angular_devkit/build_angular/src/builders/browser/schema.json
+++ b/packages/angular_devkit/build_angular/src/builders/browser/schema.json
@@ -220,6 +220,12 @@
       "enum": ["warning", "error", "ignore"],
       "default": "warning"
     },
+    "i18nDuplicateTranslation": {
+      "type": "string",
+      "description": "How to handle duplicate translations for i18n.",
+      "enum": ["warning", "error", "ignore"],
+      "default": "warning"
+    },
     "localize": {
       "description": "Translate the bundles in one or more locales.",
       "oneOf": [
diff --git a/packages/angular_devkit/build_angular/src/builders/dev-server/index.ts b/packages/angular_devkit/build_angular/src/builders/dev-server/index.ts
index 208c095bac90..bacccc93dc61 100644
--- a/packages/angular_devkit/build_angular/src/builders/dev-server/index.ts
+++ b/packages/angular_devkit/build_angular/src/builders/dev-server/index.ts
@@ -366,14 +366,22 @@ async function setupLocalize(
       compiler.hooks.thisCompilation.tap('build-angular', (compilation) => {
         if (i18n.shouldInline && i18nLoaderOptions.translation === undefined) {
           // Reload translations
-          loadTranslations(locale, localeDescription, context.workspaceRoot, loader, {
-            warn(message) {
-              addWarning(compilation, message);
-            },
-            error(message) {
-              addError(compilation, message);
+          loadTranslations(
+            locale,
+            localeDescription,
+            context.workspaceRoot,
+            loader,
+            {
+              warn(message) {
+                addWarning(compilation, message);
+              },
+              error(message) {
+                addError(compilation, message);
+              },
             },
-          });
+            undefined,
+            browserOptions.i18nDuplicateTranslation,
+          );
           i18nLoaderOptions.translation = localeDescription.translation;
         }
 
diff --git a/packages/angular_devkit/build_angular/src/builders/server/schema.json b/packages/angular_devkit/build_angular/src/builders/server/schema.json
index 0de18853499c..d4c68ecf16df 100644
--- a/packages/angular_devkit/build_angular/src/builders/server/schema.json
+++ b/packages/angular_devkit/build_angular/src/builders/server/schema.json
@@ -133,6 +133,12 @@
       "enum": ["warning", "error", "ignore"],
       "default": "warning"
     },
+    "i18nDuplicateTranslation": {
+      "type": "string",
+      "description": "How to handle duplicate translations for i18n.",
+      "enum": ["warning", "error", "ignore"],
+      "default": "warning"
+    },
     "localize": {
       "description": "Translate the bundles in one or more locales.",
       "oneOf": [
diff --git a/packages/angular_devkit/build_angular/src/utils/build-options.ts b/packages/angular_devkit/build_angular/src/utils/build-options.ts
index 68ef798bdf67..70715e8c2b7d 100644
--- a/packages/angular_devkit/build_angular/src/utils/build-options.ts
+++ b/packages/angular_devkit/build_angular/src/utils/build-options.ts
@@ -13,7 +13,7 @@ import {
   Budget,
   CrossOrigin,
   ExtraEntryPoint,
-  I18NMissingTranslation,
+  I18NTranslation,
   IndexUnion,
   InlineStyleLanguage,
   Localize,
@@ -38,7 +38,7 @@ export interface BuildOptions {
   verbose?: boolean;
   progress?: boolean;
   localize?: Localize;
-  i18nMissingTranslation?: I18NMissingTranslation;
+  i18nMissingTranslation?: I18NTranslation;
   bundleDependencies?: boolean;
   externalDependencies?: string[];
   watch?: boolean;
diff --git a/packages/angular_devkit/build_angular/src/utils/i18n-options.ts b/packages/angular_devkit/build_angular/src/utils/i18n-options.ts
index da6652062b25..0b249cb850d6 100644
--- a/packages/angular_devkit/build_angular/src/utils/i18n-options.ts
+++ b/packages/angular_devkit/build_angular/src/utils/i18n-options.ts
@@ -12,7 +12,7 @@ import fs from 'fs';
 import module from 'module';
 import os from 'os';
 import path from 'path';
-import { Schema as BrowserBuilderSchema } from '../builders/browser/schema';
+import { Schema as BrowserBuilderSchema, I18NTranslation } from '../builders/browser/schema';
 import { Schema as ServerBuilderSchema } from '../builders/server/schema';
 import { readTsconfig } from '../utils/read-tsconfig';
 import { TranslationLoader, createTranslationLoader } from './load-translations';
@@ -233,6 +233,7 @@ export async function configureI18nBuild<T extends BrowserBuilderSchema | Server
         },
       },
       usedFormats,
+      buildOptions.i18nDuplicateTranslation,
     );
 
     if (usedFormats.size > 1 && tsConfig.options.enableI18nLegacyMessageIdFormat !== false) {
@@ -282,6 +283,7 @@ export function loadTranslations(
   loader: TranslationLoader,
   logger: { warn: (message: string) => void; error: (message: string) => void },
   usedFormats?: Set<string>,
+  duplicateTranslation?: I18NTranslation,
 ) {
   for (const file of desc.files) {
     const loadResult = loader(path.join(workspaceRoot, file.path));
@@ -308,9 +310,18 @@ export function loadTranslations(
       // Merge translations
       for (const [id, message] of Object.entries(loadResult.translations)) {
         if (desc.translation[id] !== undefined) {
-          logger.warn(
-            `WARNING [${file.path}]: Duplicate translations for message '${id}' when merging`,
-          );
+          const duplicateTranslationMessage = `[${file.path}]: Duplicate translations for message '${id}' when merging.`;
+          switch (duplicateTranslation) {
+            case I18NTranslation.Ignore:
+              break;
+            case I18NTranslation.Error:
+              logger.error(`ERROR ${duplicateTranslationMessage}`);
+              break;
+            case I18NTranslation.Warning:
+            default:
+              logger.warn(`WARNING ${duplicateTranslationMessage}`);
+              break;
+          }
         }
         desc.translation[id] = message;
       }
diff --git a/tests/legacy-cli/e2e/tests/i18n/ivy-localize-merging.ts b/tests/legacy-cli/e2e/tests/i18n/ivy-localize-merging.ts
index 622d12d5bff8..a336f76c422b 100644
--- a/tests/legacy-cli/e2e/tests/i18n/ivy-localize-merging.ts
+++ b/tests/legacy-cli/e2e/tests/i18n/ivy-localize-merging.ts
@@ -8,22 +8,20 @@
 
 import { ng } from '../../utils/process';
 import { updateJsonFile } from '../../utils/project';
+import { expectToFail } from '../../utils/utils';
 import { setupI18nConfig } from './setup';
 
-export default async function() {
+export default async function () {
   // Setup i18n tests and config.
   await setupI18nConfig();
 
   // Update angular.json
-  await updateJsonFile('angular.json', workspaceJson => {
+  await updateJsonFile('angular.json', (workspaceJson) => {
     const appProject = workspaceJson.projects['test-project'];
     // tslint:disable-next-line: no-any
     const i18n: Record<string, any> = appProject.i18n;
 
-    i18n.locales['fr'] = [
-      i18n.locales['fr'],
-      i18n.locales['fr'],
-    ]
+    i18n.locales['fr'] = [i18n.locales['fr'], i18n.locales['fr']];
     appProject.architect['build'].options.localize = ['fr'];
   });
 
@@ -32,5 +30,18 @@ export default async function() {
     throw new Error('duplicate translations warning not shown');
   }
 
+  await updateJsonFile('angular.json', (workspaceJson) => {
+    const appProject = workspaceJson.projects['test-project'];
+    appProject.architect['build'].options.i18nDuplicateTranslation = 'error';
+  });
+  await expectToFail(() => ng('build'));
 
+  await updateJsonFile('angular.json', (workspaceJson) => {
+    const appProject = workspaceJson.projects['test-project'];
+    appProject.architect['build'].options.i18nDuplicateTranslation = 'ignore';
+  });
+  const { stderr: err2 } = await ng('build');
+  if (err2.includes('Duplicate translations for message')) {
+    throw new Error('duplicate translations message not ignore');
+  }
 }