The extra detail is interesting. It's clear it was more than simply using the same slip over and over again but he made copies of it. Also I guess the 154 transactions in a two month period must have meant - and they say he was doing it several times a day - probably whilst on his police duties.
He wasn't making copies, he was scanning and then using a fake coupon (i.e. a bit of scrap paper) to fool the machine into thinking the coupon was handed over.
Now I presume the illegal bit was the above.
If he had actually inserted the real coupons each time then I presume he wouldn't have broken any laws, but might have still been in abuse of the Clubcard.
OK let me recall the circumstances of that Temporary Clubcard extravaganza:
It was possible to get one voucher per transaction by using a new Clubcard each time. Now in theory you could get a voucher for spending 1p on a small carrot or something. If it was done repeatedly, does that constitute fraud?