More than 4 Bigspooks can spawn... somehow?

I don't have a good idea of what the cause could be, but I've used Bigspooks to help kill Bee Queen. I set up 8 graves so that if I lost any I'd quickly get reinforcements, and while the fight (almost) always begins with just 4 spawned, somehow I end up with 6 or 7 in play. It happens most often in battle, and I think distance might be part of it? Because Bee Queen likes to slowly drag you away from her spawn point, and it seems like the further I get, the more Bigspooks end up in the fight. But I did notice once before the fight even started that there was a fifth one already spawned somehow.