Slain Respawned Ender Dragon acting like original

I respawned the Ender Dragon and upon killing it, a new Dragon Egg spawned on the nest after I had already removed the first one prior to respawning the Dragon. I also received about 67 levels worth of XP, which is only supposed to happen upon killing the first Ender Dragon. 

(I have 2 Dragon Eggs in my world and have received 67 levels of XP from both Ender Dragon fights)