Hello Theo,

At the present time there isn't a way to manually create a new duplicate group. This is something we hope to add in a future update.

In the meantime you would need to add the item(s) to an existing group.

You could designate an existing duplicate group as a 'catch-all' group and assign any of the stray items to that duplicate group. You would then know where to find any of the stray items.

Best regards,

Jeff Brunton