Vendor response:

This was just a simple case of the incorrect BCG being packaged up and shipped out. Most of the bolt carrier groups we carry, you can see are barely marked at all, and are easily mixed up.

CMT BCG’s are not marked, LMT, are not obviously marked, Stag, etc etc. To a trained eye, sure you might see a difference if you look closely enough.
The OP was not shipped a "fake" LMT BCG; he was shipped the wrong BCG altogether by accident, and a correct replacement is on the way.

An avoidable drama. Case closed.

AC