Seeing as one of them popping is a often a wipe, getting two back to back ticking often feels like a no-win scenario.
I just had this on Chasm Station where, as we cleared the 1st DH at the bottom of the room after 1st medicae, the 2nd started ticking while Twins + Scab Captain spawned.
Maybe look at spacing them out or increasing the timer? Cause it sucks to be playing fine and then hard wipe to something that feels unreasonable.
We had some bugs also, such as the ritual DH spawned on the top an actual DH…Our ogryn nuked the ritual with his frag bomb, killed the ritual and woke up the other DH as a result. Just one of many examples why Havoc needs more bug fixes and polish.