What does the "2x" mean?

I'm looking at Kenco today, and there is a little "2x" symbol in the top corner, next to the pack size. I don't understand what it means (on a lot of websites if you mouse-over a button like this it gives a popup explaining it). It appears to affect the price per 100g, by halving it from what it should be. The £4.50 is per pack, not per 2 packs, but the price per 100g seems to be assuming £4.50 is the price per 2 packs. I'm having the same confusion with Kenco Rich and Kenco Smooth.