Is changing the sync target of two machines with identical data supported?

Let's assume the Joplin databases of two machines A and B are synchronized (with OneDrive as sync target). If I now switch the sync target of machine A from OneDrive to Dropbox then machine A will upload everything to Dropbox. Once finished, what happens if I now change the sync target of machine B to Dropbox, too? Machine B actually contains data identical to machine A and the new Dropbox target. Should I expect strange behavior after this procedure?

I ask because I read in some posts that people uninstall Joplin and delete local databases before they change the sync target. Is this really necessary?