The Preexisting tab of the Import Wizard lists policies that are already saved to the SQL Safe Repository.
Choose to overwrite or skip the import of these conflicting policies. You can do it one by one or select a couple of policies then click on the Overwrite Selected or Skip Selected options at the bottom of the wizard.
Use the 
filter arrow to order the listed policies by name, type, and action.
The progress bar at the bottom shows the overwritten, skipped, and pending policies and the total number of policies.
Once you overwrite or skip the existing policies, click NEXT to review the SQL Instances.