The MMC2 was B&O's second best cartridge. It is essentially the same as their top-line cartridge (MMC1) except it did not fall within certain test parameters when tested by B&O.
These are very good cartridges, and not generally found on an RX2, they usually came with the MMC3/MMC4/MMC5.
It is a "contact-line" stylus with a beryllium cantilever.
The cartridge can be removed from the tonearm by gently holding the tonearm with one hand and using the other hand to pull/wiggle the cartridge off the arm.
I have a B&O BG9000 which is their top-pline turntable (tangential tracker) and both MMC2 and MMC1 cartridges. The MMC2 sells for about $400-500 now abd the MMC1 can be found for $750+
You should have the cartridge inspected under a microscope. If the stylus is good, you snagged a pretty nice piece. You could really do that cartridge justice by finding one of B&O's tangential tracking turntables to use it on.
Contact me offline if you need/want more info...
-RW- (rlwainwright AT gmail DOT com)