iPhone asking for random Apple IDs to update apps?

Hi!

My brother is having a strange problem with his iPhone ). He has only had it for a few weeks and was trying to update his apps today when he was asked to sign in with a different Apple ID. He has no idea who the person is so it is not a friend that downloaded the app using their own ID. This happened multiple times with different apps and different Apple IDs. He has not been able to update these particular apps. I suggested that he delete them and reinstall them, but I am really curious as to why this is happening. A Verizon store employee transferred data from his old phone to the new one so perhaps that caused it? I would appreciate any insight!

Thanks!!