Oh. What's the purpose of dual exhaust ports?
As far as I can tell, it's done so that you can have 2 exhaust systems, which presumable make the bike look "symmetrical" or something like that.
There's no valid performance reason to have it.
I think it's a styling thing.
RE was not the only company to do it. There were some others that did it, too.
Adds about 30 pounds of needless weight to the bike too, from the extra unnecessary exhaust pipe and muffler.
If it were a 4-valve engine, then there might be some technical reason for it.