Modify error message on duplicate info

The users did not understand what to do when shown the default error
report box telling them that their information was already registered.
This commit shows a less "scary" box with less text, telling them what
to do in addition to what the problem is. Hopefully that helps.

This can be removed in the future when the backend design allows us to
save this information so that the hosts can make a decision for these
cases.

Resolves: GREG-324