I have/had both. The Kareen is a true clone, the parts probably made by FEG. They are good, solid pistols. Yours was probably a private pistol turned in to the Israeli police at some point, and sounds pretty beat. FM90s are about 95% clones and pretty good shooters. I think their triggers are the best in the HP world. I wasn't happy with the metallurgy of my FM90 and sold it.
Hope this helps.