There is an older model of the DP-DMX20L that is only a dimmer pack. I have 3 of these, and I absolutely enjoy them. Having switching capability would be nice, but it's never been an issue for me.
Mine are labelled AmericanDJ and Elation. I think you may have gotten older units? They've been making them with the switching option for some time now, I think at least a couple of years.