Curious. I've had two FILCOs from the same batch develop bad keys that behave exactly per the OP. One was clearly due to the switch being soldered out of place (it snapped down into place and died), but I was wondering about why this keyboard (at home) also developed a doubling-up key, at exactly the same time, from a switch that appears correctly mounted (unlike many of the switches that are bendy, this one is rock solid).
Still trying to figure out why I get double 'r's a lot – never happens if I alternate 'r' and enter, but does occur during typing. As time passes it seems more and more certain that it's the switch that's on the fritz, but why can't I ever repeat the fault in testing? (Two FILCOs from the same batch that both got bad 'r' switches at the same time as well ...)
Cherry switches seem a bit iffy. The clickers in the MX blues are all wearing out (after just under two years), as many now rattle more than click. A lot of the brown switches in the other keyboard were quite scrapy from new, audibly so, though the edge did wear off the sound. Manufacturing standards at Cherry don't seem all that good – I guess costs have to be kept down. I don't even know whether they're still German made, as the quality seems awfully low for anything coming out of Germany. And now I've got one faulty switch, one mismounted switch and two seemingly on the blink ...
I don't know if I can be bothered with Cherry MX brown any more – I may stick with my Realforce and see how that fares after a couple of years of heavy office use. There isn't a lot to fail, although domes can split ... I just wish that I could still buy keyboards that last, like my old Tulip blue ALPS that's as good now as it must have been the day it was made, smooth, clean feel and 102 fully-functioning keys (and that's after years in a damp, dusty corner). After all, that was part of the point of spending all that money on these contraptions ;-)