I agree. One target would be more than fair as I seem to break just as many with my 20 also. Most 20 gauge loads are 7/8 oz. while 12 gauge are usually 1 or 1 1/8 so your only really losing 1/8 -1/4oz of shot. However, if I were shooting for that kind of money, and I think most people will agree, I will be shooting a 12. That 1/8-1/4oz of shot could be the one target difference that wins me the money. Any other time I'd shoot the 20 gauge. Tough call though!
Well, maybe it depends on your game. I shoot competition skeet mostly. My
thought is , if I can not score well with the twenty gauge the twelve would not make a difference. In fact When I shoot doubles the recoil recovery is much easier between shots. I have shot nice trap scores with the twenty by changing shot size and chokes. Love trap doubles also.