When you get the merge screen, which will force you into the lower sequence, you see the 'data' portion with names, dates, locations, side by side so you can choose which to use, if there is a discrepancy, as well as parents. If parents disagree, it may mean the parents are also duplicated and merge should be proposed if they are the same.
Biography will have one profile text, then the other profile text, then the Sources in the same way, so you need to 'clean up' the profile, if any of the biography or Sources was duplicated on both profiles, they should be removed and / merged into one entry.
The merged profile will have both PMs and any Trusted List.