Comment 7 for bug 132812

How about this? We could consider the backup file to be "attached" to the main file, and both would normally be shown as one icon. If you select the icon, it will say something like this in the status bar:

    "To do list.txt" (and 1 hidden attachment) selected

If you then move or rename this, the backup file gets moved or renamed, too. If you want to work with each file separately, you can open the context menu and click "Expand", and any selected files with attachments will be expanded to show all the actual files, with lines connecting them to show which ones are attached. Or we could use the "Show hidden files" command to expand these into separate files. (Or both.) Then in this mode you can work with each file individually if you need to.

Other possible applications:

This functionality would also be useful for HTML files with folders of content attached. Like in Firefox when you save as "Web Page, complete", you will get a file like "My Homepage.html" and a folder like "My Homepage_files" which contains associated content. In Windows, these are treated as a group in some ways (deleting one deletes both), but not in others (renaming pops up a dialog). This "grouped file" functionality could be used for these, too.

In OS X, extra file data ("resource fork") is stored in ._whatever files. These could be "connected" to the original file, too, so that moving or renaming files in Ubuntu maintains their metadata for later use in OS X.

Other similar things: .info files, "bundles", application directories, ... There are probably other, better uses I'm not thinking of.