Duplicate aliases/member names not being picked up in metadata validation

Summary:

One of our users was unable to post a journal after a recent deployment it turns out we had a conflict because of duplicate aliases in the same dimension,

In the old on premise version of planning this would have resulted in an error message on deployment or at the very least a failure on validation.

Our app isn't DSO. Has anyone else come across this - we're using EDMCS for metadata mastering - so I'm going to look at custom validations in there.

Has anyone also come cross the same issue if so what was your workaround (other than not making mistakes.....)