Ever modified something in IIS and then wanted to revert but forgot what setting it actually was? Or ever been in a lot of trouble, you know somebody changed something, but not what? Well seems IIS keeps backups of the configuration files for you!
You can find them in c:\inetpub\history
I don’t think they’ll be created when you manually modify those xml configuration files. Might be interesting to check if performing modifications through appcmd make it here. I would guess so.