We were ordering the birthday cake for oldest child's party this weekend, when Youngest overheard. Miffed, he asked in a plaintive voice, "Why does he get two birthday cakes?!"
We had gotten a very small one for the actual day of Oldest's birthday, knowing his party was 2 weeks away. Youngest's birthday party was a week before his actual birthday, so we had not done the same for him. Just one cake.
DH looked in surprise at Youngest, and clarified, "This means you get to have some of 2 of his birthday cakes, instead of just one. What are you really having a problem with?"
Youngest thought about it, and retracted his complaint. The principle seemed a lot less important than the potential for chocolate.