Blizzard is trying to address the issue in its latest round of tweaks to the account rollback feature.
Here’s the official announcement from Blizzard:
Starting on Tuesday, April 2, all character equipment including weapons and armor restored via the Diablo III rollback service will become bound to the restored account.
This means restored items cannot be traded with other players or posted on the auction house, but that they can still be shared with other characters on the account and sold to merchant NPCs.
So hurry up if you are in a duping mood, you have till April 2 to do it!