I have a pair of toggle light switches that are top and bottom, rather than the side by side that you usually see. They are part of the same unit/housing, which has a face profile just like duplex receptacles (part square, part rounded). However they control two different lights in my bathroom; one controls a fan/light combo unit (no heat) and the other a pair of sconces yet to be installed. I would like to be able to control the sconces on a dimmer switch. If the two switches were separate units side by side, that would be fairly simple, swap out the traditional toggle for a dimmer. But since they are currently on one unit, is it possible to put two small top/bottom switches in the place of this one unit? Or am I stuck with them the way they are (unless I swap out for a bigger junction box). Thanks.