Framing over half insulated wall

[dcervoni]

In one half of my basement I've kept the approx. 4 ft of fiberglass insulation and vapor barrier (to frost line) that the builder installed and I framed over it with 2x4's. My question is can I place vapor barrier over the 2X4's before I drywall or is it not a good idea because there is already 4 ft. of barrier behind it.

Thanks - D. Cervoni