I am running version 8.1.3 and i am sure that when searched for a user account it returned the onPrem AD account but also the Azure account. Am i going mad that it was a thing?
There were many web interface enhancements / optimizations introduced in 8.1.3. For hybrid objects, this seems to be the behavior now. For items that are not hybrid, you will still see both onprem and Azure objects if the search criteria matches.