That's a good question that I really never considered. However, I would have to think that the barrels are different. A quick Google search turned up no left handed Mossberg barrels. But looking at schematics online they do look different to me.
I would call Mossberg directly. I know they make the field/deer combo in left hand.... So they do make left handed slug barrels.
Call them up and see . Let us know what they tell you . Welcome to HNI
-Jake