In the 50's they did it a lot before bigger motors were available.I have a 57 18ft Crestliner utility rated for 70 hp. just right for 2 35's.
by 57 Merc had a 4 cylinder 40 hp and a 6 cylinder 60 hp.
Definitely cool. But would be slower the a single 70 also use more gas
than a 70.Then there is the complications and maintenance.