Searching by names can show duplicates, of course. So a good habit could be to show newcomers how to check the npub; because this is quite long, we can use and usually trust its "fingerprint", for example, the common four starting and ending chars: npubXXXX...ZZZZ.
Me: Mom, which username did you choose?
Mom: Maria, I used a purple cat as an avatar!
Me: Ehm... a lot of Purple-Cat-Marias around, check in your profile, it is npubXXXX...ZZZZ?
Mom: Yes!
Maybe the "fingerprint" idea could be standardized in a NIP and pushed as best practice.