My iPhoto (iLife 11, version 9.1.5) committed sepuku. No fear, I have backups.
The backups I restored, instead of having 182GB of poorly taken pictures, ended up taking 276GB. Something failed with the restore procedure. The backup application I'm using is CrashPlan (and I do have an open support request about this with them and they are looking into it). I restored the whole directory of pictures (the iPhoto Library) into another directory and opened it with iPhoto (by starting it while pressing alt/option).
I restarted iPhoto in maintenance mode (by pressing alt and command when starting iPhoto) and selected all options but the restore from backups. After regenerating everything, it claimed there were 27000 new pictures in there somewhere. As expected. I was offered to import them. I selected yes. Asmost all the pictures were duplicates and they are being ignored.
Now, my concern is, those pics must still be laying around. Any ideas how to find them and delete them?
Update: in this screenshot you can see the differences in sizes between the original library, now broken, the recovered and fixed library and re-recovered, unfixed library: