this might sound dum but why do our engines have 2 spark pugs per rotor? what do the main and trailing plugs do?

 

Fuel efficiency...Both leadings fire at the same time, which means one is actually acting as a "trailing" at that point...

And I've heard a couple of the old-timers on here tell me that the plugs actually fire three times per rotor face. Wrap your head around that one, lol...

 

Fuel doesn't instantaneously combust. The spark ignites the fuel nearest to it and the burning fuel spreads out and ignites the fuel around it. Since the rotary has a long combustion chamber, having one spark plug wouldn't burn all of the fuel before it's pushed out the exhaust port. So, two spark plugs are used to help burn all the fuel in the combustion chamber. This is also why the 787b has three spark plugs.

 

Precisely