I have for a long time. Back in my professional days I kept a second snare next to the kit as I tuned very high and I hit very hard (getting that incredible back-beat WHACK! that was part of my trademark sound). If a show was long enough, I would inevitably break the head and needed something to take over while my drum tech replaced the head. I would remove the main snare and hand it to my tech and play the second where it was to save time by not moving it around. It was easier to move the mic than the snare drum.
When I took up playing again, I wanted to expand the style of music I was able to perform so I now keep a second, darker snare tuned big and phat as a contrast to my preference for a sharp, bright snare which gives that old "CRACK" I love so much. I don't play as hard anymore and I don't tune quite as high. Also, the heads are better manufactured now and last longer.
So, yes, I have two snared.
It is pretty common in the prog-rock and studio player circles. The signature "Omar Hakin" snare was designed specifically as a softer, darker snare for the man it is named after. The flexibility to get truly different snare sounds is growing as I am now seeing even the basic 4-piece kit players putting a second snare in their rig.