JW 125 and JW 138 are the matrix numbers. For some reason, they have been stamped into the labels mirror-inverted. The A side stamp says 125-2, because it must be take 2 of matrix JW 125. I can't see a -2 on the B side, but that was also a take 2 per http://www.mgthomas.co.uk/Records/LabelPages/Eclipse8.htm