This is how it often works! You may get first "block used twice" error. When validated again, you may get "out of range" error and after a new attempt it may finally be OK. And sometimes Disksalv may even crash during operation. The worst disk fault I had years ago was finally repaired on the fifth attempt I think. That's why I keep my backups fresh, it's much easier to make a 15 min backup session than use hours to fix crashed partitions.
