Monsterology Question

Suppose somebody gives a hydra a few extra heads, as one does, but then refrains from slaying it. Will it keep them? Will some fall off? Is the original head the one that stays, or does a fresh one take the main place, and if so, will the hydra have a lopsided appearance forever? Based on the imagery, I'm going to say that last one is definitely what happens.

Addendum

"A man can be eaten but once, but a pummeling may be profitably multiplied." - an evil wizard deciding whether to give his horrible creations extra heads or arms

Anatomical Musings

In the light of day, thousands of years later, I'm starting to think that having multiple heads doesn't make a monster any scarier than it would be otherwise.

Addendum

Nobody ever uses the Stymphalian birds. They're right not to. As to the Hydra, or a hydra if you want to be that way about it, imagine a hydra chef with its many heads gripping various spoons and pans.