factory dual exhaust???

I just bought a used 2000 silverado 2500 with 6.0 liter and was wanting to upgrade the exhaust system and I was surprised to see 2 pipes running from the motor complete with 2 converters but they run into single big gm muffler with 1 tailpipe. If it had 2 mufflers it would be a complete dual system had anyone seen a exhaust like this ?previous owner says he did not upgrade

That is the factory setup. Its for emissions so there is a catalytic convertor for each bank of the engine.

thanks for the info I was confused because previous post about exhaust have talked about Y pipe but mine doesn't have Y but 2 seperate pipes coming from engine. I just wonder why they didn't go ahead and make it dual all the way out. All I really have to do is add another muffler and I will have duals