Keep in mind that some don't understand the merge process, and to a certain extent we're all learning, so it's good to work with whomever sent the request, ask them if you can help, and see what they intended. Most times it's just that they overlooked something obvious to you but not to them. Sometimes they think a merge is the way to gain access to a profile. Sometimes the profiles are private and they're guessing. Either way, it's an opportunity to help and clear up misunderstandings. But do reject merges that are invalid first - that should prevent something accidental from going too far.