Quote Originally Posted by Penner
Also, have they explained what happens if multiple people eat from a Devil Fruit?
I believe this has only really been addressed in an interview with Oda. Supposedly it only takes one bite to completely inherit the fruit's ability, and the fruit becomes useless after that one bite too.

Or if u eat one and gain a power, then eat another one after that.. does nothing happen or does the new power overwrite the old one, or do they cancel each other out and u become powerless again?
The wolf CP9 guy references this. I think eating a second devil's fruit is supposed to kill you or something.