Someone reportet the bug in a german bug thread:
Sometimes it happens. He's eating some food and than it happens.
His Minecraft is giving his user once again a food item. But he's not right-clicking, also there aren't any particles of the food.
Normaly while you right-click with a food item you only eat it, only at the moment while you click.
But the Minecraft of him gave him more food than he want to.
I don't know how to reproduce it... It just happens sometimes.
Some users had this bug in 1.3.2 too.
Related issues
Comments

This sounds like this bug. Sometimes eating one food causes two foods to be consumed.