Why exactly did hey recreated a flashback scene? Was it because it was in black and white? Or because the searching for the tape and putting into new show would be too expensive.??
I think that in 1968 they needed to emphasize something different from what they were getting at in 1967, so they had to rewrite the scene. I've never watched the two scenes one-after-the-other, so my memory is not reliable on this, but in the original, the point of the scene was that Maggie was pretending that she believed herself to be Josette when in fact she had figured out that she was Maggie, whereas in 1968, the point of the scene was Maggie's realization that Barnabas was a vampire.
And, of course, as you suggested, JWGucciEnvy, the switch between color and black & white would have been jarring.