Here's the difference:
D-Lo Brown, Kurt Angle and Jeff Jarrett all held the European Title and the Intercontinental Title at the same time. Kurt Angle went so far as to call himself the Eurocontinental Champion. But since the belts were not unified, they defended each title separately.
When RVD defeated Jeff Hardy in 2002 ... a match to unify the IC and Euro Title ... he was not considered the IC and Euro Champ. He was considered only the IC Champ because the belts were unified into one.
Similar situation here - When the BOD defeated Kanyon and DDP, they held both tag titles ... but the belts weren't unified, and they defended each title separately.
Since the Colon's unified the titles, a tag team can't defend the belts separately. They have to defend the unified belts as opposed to just the WWE Tag Titles or the World Tag Titles...
