AI sends envoys to dead allied planets

If one is playing a team game with AIs and the AI is to the point of building envoys, if you wipe out a planet owned by a player, and an AI allied with that player has an envoy there (which your fleet proceeds to kill), I've noticed that very often the AI then simply builds and sends another envoy there, despite the fact that the planet is no longer allied. So then I attack that envoy and destroy it. Then the AI builds yet another useless envoy to send there.

This isn't something that happens to just me, right? It'd be nice if this could be fixed.