Yes they do, every now and again. It is very rare. I done it near the start of the year and it was only selected stores and on selected departments like clothing, gardening, small electricals, frozen food etc. And the maximum you could double up was £25 so you ended up with £50. I got a brilliant camera which was already reduced from over £100 and only paid £19.99 for it. That was back in may maybe? I have saved £50 already again since then. It's one of my favourite loyalty cards on top of Tesco clubcard.