...I never really did understand ETC's 2 Dimmers on one module thing.
Do you mean having dimmers 1+2 on a single module, or using dimmer doublers?
Having 2 dimmers on one module just makes things easier by going in pairs. Less moving parts by having fewer things going in and out of the rack. Less cost by having to buy fewer dimmers.
If your talking about dimmer doublers...set them down, leave them alone, and don't make eye contact...just back away slowly...no one fully understands the dimmer doublers.