I asked this question over on Movies SE, but haven't gotten any bites in the 3 weeks since. Maybe I'll have better luck over here.
While watching Underworld on Netflix, I noticed that in flashbacks the original blonde Sonja (Jazmin Dammak) had been replaced by the brunette version from Underworld: Rise of the Lycans (Rhona Mitra). Obviously this was done after the release of the third film in order to make Sonja's appearance consistent across the franchise.
However, I own the Unrated Extended Cut on DVD, and it has the original blonde Sonja.
In what version or edition of the film was Sonja's scenes retconned with the new actress?