Evan, Welcome to G2G.
There is no protocol to wipe clean the public comments suggesting why a merge was needed. It's up to the individuals to remove them. There are two thoughts about this. One is that it's part of the profile history and comments should never be removed. The other is that they're redundant, because the merge is recorded in the changes "tab"
As for the note at the top of the biography, this is not strictly needed, because there is an automatic notice in the changes "tab".
If you haven't already discovered the changes tab on profiles, check a few out. It gives the history of what changes are made to a profile and who made them. The nice thing about this, is that if you change your mind, about a change, you can look back and see what was there before. I sometimes delete things, that I decide later should have been there. I'll just copy and paste from the changes section back into the bio section.
The merging process is completed by individuals, not automatic, so whoever completes the merge decides what is the best information.