i think it would be a major task to get the two channels to be identical. i emailed the guy from voodoo amp mods a couple years ago with a similar question just to see what he had to say. he said that the 2nd channel has a fixed tone stack before the tone knobs. this is similar in theory to a dumble, but not in practice because the voicing is different. he also said that it's an involved process to get rid of it.
plus, something with the power tubes changes when you switch channels (not sure on the details, maybe it's a different voltage depending on if you're in rhythm or lead).
so i guess the 2 channels are pretty different. i have never heard of anybody doing this mod.
gosh, the closes thing I heard of this and ironically is Trem-o-Verb's channel cloning.
I say "ironically" because seems like Maverick and Trem-o-Verb, although sound different both tone controls, modes, volumes works in the same principle.