Multisite cloning issue

When trying to use the Cloner plugin to clone an existing site, we receive the following error message:
"You appear to have already installed WordPress. To reinstall please clear your old database tables first."
The site is created after the clone, but it is created with a basic theme and none of the cloned users, etc. I've checked the database tables and everything appears normal. Also, creating new sites works fine...it's just a problem with cloning an existing site.