Originally Posted by
JohnDThompson
Steel only becomes fatigued when bent past its yield point. While dropping the derailleur into the spokes can bend the drive side dropout in this manner, there's nothing on the non-drive side to do the same, so the non-drive side dropout will be fine.
+1, the accidental breaking on one dropout has nothing to do with the other. To think so. would be like thinking that if you broke your right leg skiing, your left leg is probably also weak.
Side note to the OP -- if you have this welded, have the welder set a pin or small cap screw inside the slot, to position the axle where you want it. Then the left side micro adjust can be used to fine tune centering. Alternatively, he can fill some of the back of the slot moving the dead stop to where you want it, while also strengthening the dropout.