The spawn time of the dummy skeletons is too short. When you have long lasting dots down you agro the new spawning skeleton and it badly effects your dps result.
No it respawns, and gets the dots. I'm under atack for the whole time until my dots run out. After that I get my result. Only one result, otherwise i would get a very low second result. I'm one xbox though.
Put caltrops or ash cloud down and you will agro it again when it respawned. Then you have to wait till the agro is gone before you get your result. If you would get your result immediately when it dies, you would get a second one, because you did damage again for a few seconds. But its not like that...
So the only method right now is putting your dots anywhere quickly, after it has died - a little bit stupid.