There's multiple bosses because you were either with a friend, or had your field settings higher than normal.
To get around it. You either need to seperate your bosses into a seperate group- or there's an option not to autospawn the boss. You can do either of those to place the bosses where you want without multiples.
Thanks, I thought I did have the boss in a seperate group, but I'll check again tonight.
I went back and ran one of my own missions I created ages ago and got a bit of a surprise. After I defeated one of the required boss mobs in the mission I kept running into her again further into the map (5 or 6 times). I didnt design it this way, but in one way it fitted into the mission right, her dying words are always something like Ill be back
Is this normal, has there been some change in the last year or so that I now have to select to make sure a boss only appears once?