you can plumb it any way you want. Different guys will have different opinions on this like anything else. I have the same setup. What I'm doing is connecting the two tanks together and run each compressor outlet seperately directly to one tank . Don't try to connect the compressors together and then run one line into the tank. Then I'm going to run two lines out of the tank. One line is going to control the drivers side valves, and the other the pass. side valves. I'm gonna run 1/2 line between the tank and the valves, and 3/8 between the valves and bag. I'm plumbing my valves like in this pic. Also with two compressors, your gonna want a relay I think for each compressor. Suicide doors has a relay specifically for 2 compressors.
So back to your question, there's lots of ways to plumb it.
check here for compressor wiring info:
http://www.airridetalk.com/wiring-info/
heres that relay I was talking about
:
http://www.*****************/Swingers80AmpRelay.php
[IMG]http://www.*****************/images/products/Swingers80AmpRelay.jpg[/IMG]