Electronics with Dual extruder support

[blanius]

Looking to re purpose parts from crappy 2up into new printer, what electronics boards support dual extruder?

[3dkarma]

RAMPS will, but you'll need to add some more electronics if you want to be able to control a fan at the hot end. Easy enough to do but might need a change to the firmware (pin reassignment).
RUMBA can support up to 3 hot ends.
4pi can support 2.
I think the smoothieboard can support 2.
The Duet can support 5 with the Duex4 expansion.
I think the Megatronics can support 2.

Check out the list at the reprap wiki: http://reprap.org/wiki/Electronics