We are getting an error when trying to import a Confluence Space from an old system

[Colleen Grant]

We are trying to import a Confluence Space from an old system. It validates with no errors but when it is partway imported we get an error that the "space" is already used. We don't know how to find this "other" space. 

[Calvin]

Do you know if there are any "keys" between the two confluence spaces that already exist? And in the old space are all the pages uniquely named?