The rules about suppressive fire in the core rulebook explain that you can use suppressive fire from 2 guns, simply add the rounds of both to the save formula (Save = number of rounds / width of fire zone in meters). If the enemy fails their save, then they will take 1D6 rounds in random locations.
But what if you have 2 guns that do different damage? How, then, would you determine which gun's damage gets applied?
Further building on this - what if you have multiple players creating a fire zone in the same area? The RAW say
...teams should coordinate their actions and fire at the same time, placing the maximum number of rounds into the fire zone.
If the enemy gets hit, then which gun's damage gets applied?