Not sure if I see the goal.
It seems like you (or someone) wants all SVN repositories on one machine, but they want to continue accessing through 2 different machines. Is that right? If so, what's the point in putting them on one machine? Is it for some sort of backup purpose?
For the record, you can switch the source of your local svn copy with a single "svn switch --relocate old_url new_url" command. After that, they can continue using the standard "svn co" and "svn commit" sort of commands (where the URL is implied). That being the case, all repositories could live in one place. You can move a repository like so:
svnadmin dump repositoryPath > repository.dumpfile
# cd or ssh to new location #
svnadmin create repository-name
svnadmin load repository-name < repository.dumpfile
If they really want all repositories on one machine, but to access them through two machines, you could share the repository directory on the Fedora machine to the Ubuntu machine so that the ubuntu machine still manages the SVN accounts & changes, but the data physically lives on the Fedora machine.