Mystery Coin? Great Britain Proof 1970 Penny With Error Double Reverse?

OK, this coin may or may not be the real deal. I bought it quite a few years ago at auction from either Baldwin's or DNW (Noonan's) and can't find it on their auction archives anymore.
Anyway, they felt it good as did I and submitted it to PCGS much as even longer ago I had submitted a 1964 GB Penny with error double reverse to NGC (it came back as genuine MS 58). They (PCGS) declared it counterfeit, which I think I still disagree with.

Generally proof larger format coins show "manipulations" or playing with relatively more obviously. I could see no seams, or evidence of them around the outer edge or on the inside of the rim. The former occurs when two coins are cut in half and then joined together, and the latter when the obverse of one coin is milled out and a second coin has the obverse milled down and then fit into the first. The weight of this specimen is 9.19/9.20 gms versus the 9.4 gm standard.

Anyway, here are some pictures, realizing that coins are better seen in hand.