It's currently possible to restore the same space many times in a row. We should check the for the spacekey and refuse the restore if a match is found.

1. Clean DR6 install.
2. Restored "untouched" Space backup - Space A
3. Create empty new Space - Space B
4. Rename Home page of new Space B to HomeOLD
5. Move (with child) Home of Space A to Space B
6. Made Home the Home of Space B
7. Removed HomeOLD in Space B (not really necessary)
8. All looks wonderful - ie. "empty" Space A and fully populated Space B
9. Restored Space A again - as per step 2
10. When click on Space B get "The page you were trying to reach does not exist". Nothing in logs.
11. In "Browse Space" we can see the pages - when we click on any page we get the page from Space A!!!