diff --git a/.chronus/changes/standalone-skip-shell-rerun-2026-7-30-1-48-14.md b/.chronus/changes/standalone-skip-shell-rerun-2026-7-30-1-48-14.md
new file mode 100644
index 00000000000..fe489bff5d2
--- /dev/null
+++ b/.chronus/changes/standalone-skip-shell-rerun-2026-7-30-1-48-14.md
@@ -0,0 +1,7 @@
+---
+changeKind: fix
+packages:
+  - "@typespec/standalone-cli"
+---
+
+Fix install script adding duplicate PATH entries to shell config files (`.bashrc`, `.zshrc`, etc.) on subsequent runs. The script now detects if TypeSpec is already configured and skips the shell update. Also fix `--skip-shell` flag which was using an inconsistent variable name and had no effect.
diff --git a/packages/standalone/install.sh b/packages/standalone/install.sh
index 71477fd60e9..eb26cb4145e 100755
--- a/packages/standalone/install.sh
+++ b/packages/standalone/install.sh
@@ -95,7 +95,7 @@ parse_args() {
       #   shift # past value
       #   ;;
       -s | --skip-shell)
-        SKIP_SHELL="true"
+        skip_shell="true"
         shift # past argument
         ;;
       --version)
@@ -188,6 +188,10 @@ setup_shell() {
   if [ "$CURRENT_SHELL" = "zsh" ]; then
     CONF_FILE=${ZDOTDIR:-$HOME}/.zshrc
     ensure_containing_dir_exists "$CONF_FILE"
+    if grep -qF "TYPESPEC_PATH" "$CONF_FILE" 2> /dev/null; then
+      info "TypeSpec path already configured in $CONF_FILE, skipping."
+      return
+    fi
     echo "Installing for Zsh. Appending the following to $CONF_FILE:"
     {
       echo ''
@@ -201,6 +205,10 @@ setup_shell() {
   elif [ "$CURRENT_SHELL" = "fish" ]; then
     CONF_FILE=$HOME/.config/fish/conf.d/tsp.fish
     ensure_containing_dir_exists "$CONF_FILE"
+    if grep -qF "TYPESPEC_PATH" "$CONF_FILE" 2> /dev/null; then
+      info "TypeSpec path already configured in $CONF_FILE, skipping."
+      return
+    fi
     echo "Installing for Fish. Appending the following to $CONF_FILE:"
     {
       echo ''
@@ -218,6 +226,10 @@ setup_shell() {
       CONF_FILE=$HOME/.bashrc
     fi
     ensure_containing_dir_exists "$CONF_FILE"
+    if grep -qF "TYPESPEC_PATH" "$CONF_FILE" 2> /dev/null; then
+      info "TypeSpec path already configured in $CONF_FILE, skipping."
+      return
+    fi
     echo "Installing for Bash. Appending the following to $CONF_FILE:"
     {
       echo ''