If you do 4 sconces, 2 for each mirror, it will make each mirror seem its own entity, IMHO. If you do a double sconce in the middle, it seems like.....an after thought? And the sconces will not be equidistant from each other and the mirror. My OCD kicking in, I suppose. If the space between is larger than the mirrors, I think you should go with 2 separate sconces. If the space is smaller than the mirrors, I think you could go with a double light. Just make sure the spaces are fairly equidistant.

thank you cawaps, All of my mockups with the single sconce looked a little dinky. It didn't occur to me to do something linear at all. I like those lights you chose. what do you think of this type of adjustable light? i thought perhaps it might be functional in a vanity area. my daughter is still young , so it would be a while before she needs something for makeup though. but do you think it would it go?

Your current sconces are way too small for the staircase. Not sure I would go the silver route. They may fade into the white walls. Some of the new wall sconces offered by C&B and CB2 are inexpensive and especially well designed. Maybe wood sconces to complement your staircase?????

Finally havw a chance to look. Is this close? https://www.perigold.com/Visual-Comfort--Barbara-Barry-Lyric-1-Light-Armed-Sconce-BBL-2030S-L6117-K~VSCF2824.html?refid=GX442533541807-VSCF2824&device=m&ptid=950232435747&targetid=pla-950232435747&ireid=123828866&gbraid=0AAAAADLNIe2HVEhCboj6zoInBnIdMyMPw&gclid=Cj0KCQjw54iXBhCXARIsADWpsG8LeRIvTIbA3-X-geKHZtL4Leo2sReT1fzxirTFijWBecpkuNojDS8aAuiKEALw_wcB&piid=51179292