Hey Tom!
Saw ya at Carlisle, but never got to catch up with ya. Hope all is well.

YEARS ago (1993??), I looked at a 72 440 4spd, Ramcharger equipped Charger Rallye, and that car had the 71 style hood vents as well. (Sadly ,the original eng/trans were missing on that car...or I would have bought it, and probably would still own it).
As for the hood vents, my experience has been that there was a bit of overlap between years/assembly plants. Unless you can find a paint issue or some damage that would prove otherwise, I would think your Rallye probably still has it's original hood.

I've also seen a NOS 71 R/T or Superbee hood with the 73 style hood vents. I can only assume that hood was a factory crash replacement part...but it was certainly an oddity.