I reckon the JTM45 is a reissue. Notice the can cap down at the preamp end of the amp.
Most replicas/clones will stick to the original layout of having the preamp filter caps on the board.
Also the back plate has more text on it, whereas again, clones tend to mimic the 60's appearance. It also has fuse ratings for dual voltage, a modern Marshall thing.
Also notice it's had a master volume fitted.