Left, sold as Wencezlaus II gross, I think it is Karl IV. 3.02 g, 28 mm obverse: "[DEI GRATIA] REX BOEMIE KAROLUS PRIMUS" reverse: "GROSSI PRAGENSES" 1346-1378 Right, sold as Karl IV, I think it is Wencezlaus II, or likely a later copy. 2.56 g, 23 mm obverse: "DEI GRATIA REX BOEMIE WENCEZLAVS SECVNDVS" reverse: "GROSSI PRAGENSES" 1300-1305, if contemporaneous to his reign. 1300-1564 if a later copy. I think the righthand coin has been heavily clipped. Supposedly these were issued as under Wencezlaus II throughout Central Europe from 1300-1564. The fineness and weight dropped from 0.933 to about 0.333 and from ~4 to 2 g. I don't think there's any way natural wear could remove that much of the edges while leaving the surface detail mostly intact. My guess is that the earlier, heavier coins were clipped until the silver content was reduced down to the currently available debased standard. Otherwise they wouldn't have survived to stay in circulation and would have been hoarded or melted.