So far, the GFW blocks the bridges it discovers by IP:port. Therefore, you can run two bridges on your machine and if one gets discovered, the other one should still be reachable. Of course, that could change any moment.
Wow, that's a pretty huge and inexplicable oversight on their part. Hard to believe they crippled their efforts so badly by missing something so obvious, but I can't think of any reason they'd have to restrict themselves so generously on purpose. Maybe a conscripted engineer's subtle resistance sabotage? OK, whatever, hopefully it gives time for the vulnerability to be fixed before they exploit it.