Apparently pre-sale tickets can't be resold? According to a member it says:
"To assist in the prevention of resale, the name of the Adele.com member who places the order will be printed on each ticket. In order to gain entry to the venue, ticket holders will be asked to present government-issued photo ID matching the name printed on their order. This means that each ticket purchaser must enter the concert at the same time as his or her guests. Name changes will not be allowed."