Is it possible to wire 2 GFCI receptacles on 2 circuits with 12/3 wire shared neutral?
This will work as long as the breakers are not GFCI. As long as the GFCIs are after the shared neutral, you are fine.
BTW, this arrangement is called a multi wire branch circuit and you are required to use either a double (240 volt) breaker or two breakers with the handles tied together.