I've heard so many stories like this over the years. "Project X had to move all their source out of version control system Y into Z, deleted system Y, then found out Z had a corrupt version. Luckily ol' Rick had a copy on his home PC!"

This isn't confined to software. At an aerospace company I worked at, they decided to put all (paper) engineering analysis materials onto microfilm. Then they found out that the microfilm had scrambled the images out of order. Guy named Ron had fished a lot of the paper out of the trash saving that project's bacon.