Newbie, so bear with me

As I understand a four channel dimmer allows the control of 4 separate outputs from one or more combination of inputs.

Say I have two wall lights which I would treat as a pair and would never do something to one without doing to the other one (dimming or on/off), can I use single channel to control both, or, because of voltage/power considerations, I should wire into separate channels and leave at that.

Reason I ask is that I am trying to get a ballpark cost for all this stuff for new house, and there are a number of similar situations to that above.