I have a stock copy of the Checkerlads, I don't think it's a big deal. The only RCA stock copy 45 I've never seen is Judy Freeman and Blackrock "Hold On". RCA and Columbia released way more 45s than any other labels - I'm trying to remember how many 45s Columbia was releasing per year, I think it was something around 400, or 8 per week! RCA was probably in the 200-250 per year range.