My wife works at the Fed, and I can confirm that 1) the Fed does decommission/retire bills and 2) that whole process is very tightly controlled. The retired bills are typically shredded, and if you go on a tour of a Fed bank, you can get little baggies of "Fed Shreds."
So it seems very likely to me that whatever money is in the cube is decommissioned.
So it seems very likely to me that whatever money is in the cube is decommissioned.