Muesli for the mathematically challenged

I spotted this in my local Sainsbury's supermarket:



So one packet of Dorset Simply Delicious Muesli costs £2.09, but if you buy two (at £4.50) then the unit price rises to £2.25.

Is Sainsbury's trying to discourage shoppers from buying in bulk? Perhaps this is a green initiative to penalise people who use their car to do their shopping...