Each GB lose a ghost. How do you place them around the gate? Do you roll the dice for each of them to place them around the gate? Do you move them or just place them next to the gate? Do they fusion?
You should roll the PKE/Direction die for each ghost that is emerging and place them in the appropriate space next to the ghostbuster they are emerging from.
If two Galloping Ghouls, or two Gruesome Twosomes, do happen to land on the same space, they will merge into the next higher-class ghost, per normal.