The older Mossberg leverguns, Model 472 et al, although superficially resembling Marlin 336's, were of a different internal design.
Among other things, the older Mossberg's trigger traveled with the lever, ala Browning BLR, and the buttstock was held on via a throughbolt.
If Marlin had made them, Marlin sure wouldn't have changed the basic design of the trigger, just to put out a clone - they would have simply rebranded their own gun, like they did with the Glenfield for Montgomery Ward, Sears, and others.
Don't forget - They're in the gun business to make money for themselves, not waste it on a competitor.