Maybe they ship more than that and just recycle MAC's over time from a single registration.
Wow, that would be about the most shortsighted move ever! It can't be ruled out considering some of their security gaffes, but I think a miscommunication between factories might be more likely. It would explain why they are getting dupes on new products as well. Still a reputable company would stop shipping them once they became aware...
If XM/TNT actually is hell-bent on saving OUI fees, a better strategy for soneone with such low scruples might be reappropriation of someone elses OUI, one that you are unlikely (or less likely) to come across.
For instance, maybe 48-DA-96 (hex), Eddy Smart Home Solutions Inc?
No offense, Eddy.