I'm not an electrician but some thoughts... unless there is a risk of
the conductors becoming overheated for some reason I don't see why not.
I think when you have two or runs of NM in any kind of conduit what
you want to avoid is the cables pulling the same voltage, or you might
have inductive heating problems? I think the NEC goes into detail
about not pulling two cables through conduit that will be on the same
circuit??? If I am correct I think you would be OK with what you
described.