Duplicate operationId not detected

[jayvdb]

operationId | string | Unique string used to identify the operation. The id MUST be unique among all operations described in the API. The operationId value is case-sensitive. Tools and libraries MAY use the operationId to uniquely identify an operation, therefore, it is RECOMMENDED to follow common programming naming conventions.

I have OpenAPI 3.0.3 containing the following, bug raised in generator tfranzel/drf-spectacular#137, and it isnt detected as invalid.

  /oscarapi/checkout/payment-states/:
    get:
      operationId: oscarapi_checkout_payment_states_retrieve
      ...
  /oscarapi/checkout/payment-states/{id}/:
    get:
      operationId: oscarapi_checkout_payment_states_retrieve
      ...