Curse of Elements (shadow priest) bugged?

Lately I have seen some logs that clearly shows curse of elements (cast by an eye of the void from shadowpriest) stacking with mark of chaos.
somehow this feels wrong as curse of elements from shadowpriest is identical to curse of elements from warlocks and clearly curse of elements from warlock is NOT supposed to stack with mark of chaos.
This can be seen by the fact that mark of chaos can’t be applied using curse of elements, that curse of elements gets removed from a boss (regardless which WL cast it) as soon as mark of chaos gets applied and that no warlock can apply curse of elements while mark of chaos is already on a boss.
and you can’t really argue that curse of elements from a SP is a totally different buff than curse of elements from a WL and that it is supposed to stack. Both buffs do exactly the same thing, have exactly the same name and those two “different” types of curses of elements don’t stack. so obviously they aren’t meant to be two different curses but one curse that can be applied from two different sources.
Another argument would be that stacking curse of elements (SP) and mark of chaos is totally fine but stacking curse of elements (WL) from warlock A and mark of chaos from warlock B is not ok, although it would end up in exactly the same situation.

Considering all this I would assume that Eyes of the Void are misbehaving and applying curse of elements even when they aren’t supposed to due to mark of chaos.

This might not have been THAT big of a deal in phase 4 as neither shadowpriests preferred to play eye of the void nor did warlocks prefer to play mark of chaos (unless they were alone in the group) but it would have an impact on phase 5 now. Warlocks can now easily use mark of chaos, so it would be nice to have some consistency behind the mechanics. it shouldn’t matter if my buff-partner is a warlock or a shadowpriest if they bring the exact same buff… either WL curse of elements should stack with mark of chaos (which would be incongruous with everything we have seen so far) or SP curse of the elements should NOT stack.