Two dragon eggs in survival?!?!

as the title suggests, I respawned the ender dragon and she dropped another egg! This world is in survival minecraft and no mods. I have never switched to creative in this world at all. I did make a copy of my world in case i died. But I am stumped and surprised as to why this happened! I now have two dragon eggs. I have not duplicated the original (I don’t actually know how to)  I dont know if this is a bug or if its just me. I couldnt find wnyone else with this problem.