The key is keeping the overall tire diameter within the tolerance band. You can conceivably buy two altogether different types/brands of tires and still be ok.
If it all worked out correctly and the tires were maintained/rotated correctly in the normal 'Life" of a set they would all be replaced at one time.
Your in a bit of a different situation as only 2 were identified as faulty, for whatever reason, so depending on the wear on the existing tires you may be ok to run the set until the normal replacement.
For piece of mind though matching the "new" tires might not be a bad idea as you are not sure what caused the initial failure. I know the Significant Other would not be confident in the possibility of the other 2 failing.