This has been my experience on some profiles.
Sometimes when merges are requested, the attempt results in a listing for comparing conflicting and or duplicates in the parent (s) - which should be merged first.
If the there is no way to ascertain from the profile(s) which might be correct - as there are so many unsourced profiles - or profiles with just ged.com references:
1) You are stuck with completing a merge w/o correcting the parents
2) Having to research the parents and citing their records first, then doing their merges
3) Not completing the merge.
Other times there are conflicting dates/spouses etc. when the parents match.
In either case, when such a conflict exists, the person requesting a merge should be doing this work - sourcing/bio/citations first, which is not often the case.