I expect that the number of brazed dropouts that would be solid filler at the point where (I imagine) the OP cut the stay is pretty low. In fact, this one has penetration pretty far into the tube, which I think is uncommon. I boroscope my fork blades to see how I did, but I never bothered with a rear dropout. I would like it if the OP posted more pics, if available.
I doubt the same person brazed this dropout as did the part that failed.