My older brother shoots clays, and he's right handed, but uses his left eye to aim, very successfully too. I know at least three other people who do the same, although I found it awkward when i tried.
Learning to shoot with both right and left hands is tricky at first, but soon becomes natural. Unfortunately, these days, i can only use my right hand, with the second finger on the trigger, as my left hand is totally knackered !