This doesn't make much sense... yes, you can have two fully operational launch sites in different geographical locations but the payload can't be in two places at once. If you have bad weather where the payload is then you won't launch until after is passed.
The plane can take off ahead of the bad weather and go to where weather is predicted to be better. Or, the plane can take off, go to where weather is better, then take off and fly above the troposphere in the original location and launch on time and on place.
