Raj -- in that case the pilot says to the second owner "I apologize but the owner before you took all the ...." Since we are in XXX, Ark. and can't get restocked even by our caterer we apoligize (and maybe offer a free ugradein the future??) Honesty is the best policy and most owners are capable of understanding if told the truth.
In my opinion that is not good enough. No Owner should have to ride on a plane that is not stocked properly. Thats why I always carry at least a little bit of extra stock (so that I can treat the owner properly).
Some pilots agree with me and some don't. What is the correct answer? Who knows. I guess somewhere in between.