It's almost comical how Lakers fans, out of all people, is trying to trump up the importance of repeats, in an attempt to reduce the legacy of Duncan.
Let's break this down logically, there are really two types of teams that win championships:
1) A team built around a player so dominant that any injuries or major slumps to key pieces around him is inconsequential to winning a championship. So far, we have Hakeem in 94, Duncan in 03, and that's pretty much it. Jordan had Pippen for all six of his championships, Shaq and MVPau had Kobe, Magic and Kareem had each other, Bird had the big 3, Garnett and Pierce had each other plus Allen, Lebron had Wade, Wade had Shaq.
2) A team that is so balanced, that reduced outputs from any key players is inconsequential. Teams such as 04 Pistons, 14 Spurs, 11 Mavs (though you can argue with Dirk, they belong to the first group), late 80s Pistons.
Now look at those criteria. 94 Hakeem repeated, but only after they got Drexler in a trade. 04 Spurs didn't repeat, because the Lakers smartly closed the lane on Parker and figured they can play 4 or 5 on 1 on Duncan.
The teams that repeated are teams that had so much talent when compared to their compe ion, that they can go through bad series from their alpha or beta (96 Jordan vs. Sonics, Shaq getting shut down by the twin towers in 01 or 02, 40% shooting from Kobe in any one of the playoff series he played in, Lebron's balls shrinking, Dirk being guarded heavily vs. the Heat) that the rest of the group can step up and dominate, because they have enough replaceable parts to weather injuries and slumps.
So using the repeat argue to diminish the legacy of Duncan makes no sense, as, if anything, the lack of a repeat actually speaks to how Duncan, with all his brilliance, led very beatable TEAMS to five les (or four, depending how you look at 14), single-handedly willing his teams to le after le, whereas players who repeated multiple times (Kobe is the only one here, as Jordan threepeated twice but with the core intact for both teams) actually get to coattail-ride dominant teams to these les.