Don't know the best way to describe the deal but ratatouille is £15 and cars is £14.86. When these are both scanned through the checkout they come to £20 for the lot. Only seen this in store.
For each other, cheapest place i can find it is
Cars - Sendit - £17.89
Ratatouille - Bangcd - £15.99
Even if you wanted to buy these seperately, you are cheaper going to Asda with them at £14.86 and £15.00 respectively.
Proof added below