Actually, you do make a little extra dual mining. The extra 1% fee is about one-third to one-half of the income from the second coin. But if you factor in the extra power consumption you might be right. Dual mining uses quite a bit more power. Also it stresses the cards more and might cause earlier GPU failure. I stopped dual mining for these reasons and it destroyed one of my power supplies. I added a GPU to my rig. The PSU should have been able to handle the extra power but the PSU turned off and would never turn off again. Currently it is in service and waiting for a new replacement. So you are probably correct in the fact that dual mining is probably not worth it when you consider all the factors involved.