I get mine from the work charity tuck shop, so could be a few weeks old.
The building is warm so it was nicely soft but not too sticky. I have had many a double decker in the past where the normally soft layer is hard and brittle.
Double Deckers are good. Fruit and Nut Cadbury's is pretty awesome. Mmm. I don't like Cadbury's Caramel chocolates, preter Galaxy for Caramel, and any other Galaxy choccies.