I have two Banshees here, one is a Banshee in reference layout (AGP SG-RAM, here is a phto), the other is an AGP-card in non reference layout (AGP SG-RAM, too, but the PCB is much smaller, I can take a photo tomorrow).
What's odd is that both cards have the same FCC-ID "FQI3DBSSGAGP" which identify them as Joytech Banshee. ???

Does anybody know another example of this oddity?

Yes, that's exactly the card I have but mine has a fan on a plate (no fins at all, only a plate) instead of a small heatsink.

If you compare the two FCC-IDs of your cards they are identical, too. I think your "MSI Banshee" is only a Joytech with a heatsink from an MSI-Mainboard.

My presumption: the string above the FCC-ID contains the revision since the bigger cards have "A2" (mine) respectively "A3" (yours) in the string, both smaller cards have "B2" in that string so the smaller cards are later revisions. The date code of the cards strengthen my presumption because both smaller cards are dated 5th week of 1999 but the bigger cards 43rd (mine) respectively 49th (yours) week of 1998.

Edited:

Then I need to get an original Joytech heatsink for my card  It won't be easy...

yeah just imagine! i bought it at an ebay powerseller (over 15000 feedback) as fully functional... and they do not rip off that RMA record from MSI... lol... At the back of the card there is a long scratch, but not too deep. It may be repaired at MSI...