souvenier mugs in parks?

[buffer]

We are staying in ASMo in November, travelling with Virgin. We get 2 free souvenier mugs per room. I know we can use these in our Resort, but can we use these in the parks to get drinks at reduced rates. I am sure I have seen people before handing these in at the drink stalls inside the parks?

 

[disneyag]

The hotel mugs can only be refilled at your hotel.