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.