You're both right about the Changes record of a profile that has its LNAB field edited. Before you edit a LNAB field, copy the URL for the Changes tab & include that link in the biography. When you edit the LNAB field, the changes for the old name/WikiTree ID are not deleted from WikiTree, but finding them can be a problem if you don't remember what the previous WikiTree ID was, because the Changes page for the new profile doesn't tell you (at least it didn't in the last profile I changed the name for).
Cheers,
Liz
P.S. to Philip - Yes, a single profile should be selected before any merging: even if it may not be the best LNAB, just pick one & merge all the duplicates directly into it until you figure out what the LNAB should be. When you do, change the LNAB to it. That gives only two redirects for most profiles: one redirect for all the duplicates into the chosen target profile and then a second redirect for them when the LNAB is changed.