Joomla to Drupal module - migrating issues
From the sounds of it, the module was not uninstalled correctly. You should first disable the module, then when the modules page reloads, uninstall it.  During the uninstall process is when hook_uninstall() is run and the database tables and any saved variables (from the variable table) should be deleted.  

If you didn't uninstall the module correctly, Drupal never performed these actions, and therefore still believed the module was installed.  Since it believed the module was already installed, the database tables would not be created.

For more information regarding uninstalling modules see the article: Uninstalling Modules