Transfer duck stamp between licenses?

I bought a duck stamp, attached it to my 2013 Sportsman's Package license, and signed the face of it (as per the instructions that come with the stamp). Now that I have my 2014 license, I am wondering if I have to buy a new duck stamp (even though the old one is still valid). Can I just keep the old license (with current duck stamp attached) in my possession?
Answer: 
Federal duck stamps are valid July 1 of one year through June 30 of the next.  You can carry it with you during the spring/winter waterfowl seasons.  The stamp isn't associated with a particular license number, but with the hunter who has signed it.  You can carry it with you for the time it is valid as long as it is signed.  
Answered on: 
Friday, April 18, 2014 - 3:45 PM MDT