That sounds like a double whammy that I'm familiar with. They always prefer what you have versus what they have (even when they're identical!) and they always love to forage inside boxes and such. Beaker was just being the good AG that he is!
I know that game all too well, this morning we had apple crepes for breakfast. I gave a few cooked apples to Sheeba, putting them in her vegetable/fruit dish. She saw me put them in and eventually went down to check them out, after throwing them on the floor she comes up and watches us eat. Of course she eats with gusto the same apples, as long as she thinks they come from my plate! Pretty funny!!