When you issue the checkin command from a snapshot view, the request is handled as follows:
For any other instance of the file loaded into a snapshot view, the new version is copied from the VOB into your view. (If your load rules specify a hard-linked element that appears in more than one VOB location, the element is copied into each of the appropriate locations in your view directory tree.)
When you check in a directory from a snapshot view, a copy of the element is added to all instances of a hard-linked parent directory loaded in your view.