This same offer is on in Morrisons too. Just been in store and got 2 for £15.
Seems to suggest that only baby's over 1 should drink cows milk. I take it that means drinking it all the time, as my 6 month old is starting to have cows milk on some breakfast things (advice from a baby food book) but with a formula bottle as a drink.
Note that all the baby milk in Lidl is 800g and not 900g as is found everywhere else. 2 off 900g for £15 total @ Asda = £0.83/100g Where 800g @ Lidl for £7.99 = £1.00/100g Even at the regular price of £9 @ Asda, the price per 100g is pretty much the same as Lidl (as you get an extra 100g for the additional £1.01).
This offer also applies to sma follow on