Can an orthodox jew smoke a joint with two kinds of weed in it?

Two types of pot would still be two of the same seeds - it's the same plant, even if it's a different varietal. So it would not be prohibited according to the torah. However, there are some opinions that smoking any pot at all is prohibited, because it is harmful to the body and takes away your full ability and drive to study torah - in the same way that you should avoid drunkenness.