I don't understand why you would have problems grwoing two diff strains of mj at the same time, unless of course, one is flowering and the other is vegging. In which case, you might want to try my idea: I like to call it "Dividing Canaan" I divide my grow room with a mylar curtain and make sure the other side is entirely light proofed. I keep my mothers on one side while they flower on 12/12, then slide my light over (on a bar attached to the ceiling with chains hanging that I just slide over) to the other side of the room where my clones are. I open the curtains and position the light over both mothers and clones so that they share the same light for 12 hours, but leave the light on for an additional 6 hours after sliding it over to the clone side, so my clones get 18/6, and the mothers are not disturbed during their beauty sleep.