When you go to merge two profiles with different names, Read the boxes at the top (the orange ones with the white writing) One of them asks if so and so is the correct LNAB if not reverse the merge with a click on link to do just that.
So decide which is the correct Last name at birth, and merge into that, ignore the lowest number (that's for profiles with the same spelling)
You can also in the merge and match page put the one you want to merge away into the top box, put the one you want to keep in the lower box.
You will also have to type in some kind of explanation, before it will merge