Separating groups contacts from General Contactss

I have a “General” contact list and 10 different “Groups”. For some reason, and I think it may have happened when I transferred the csv files from Thunderbird, the “Groups” appear within the “General” contact list. For instance as “artists” or “copywriters” or “Marketing”. The problem I have is that these “Group” members also appear in the “General” list, where they also belong, when a “general” mass mailing goes out.

These “Groups” do appear separately on the “CONTACT” list on the left hand side as folders because I put them there in the mistaken belief that I was extracting them as distinct and separate folders, but when i click on them they pop up in the “General” list.

How do I separate them from the “General” list into distinct and separate folders?

In practice I can still send out to the separate Groups; but for the sake of tidiness I want them out of the General list altogether, so that i can deduplicate the General list without fear of deleting “Group” members who are also on this list, therefore leaving empty “Group” categories, with no members. Or will i be able to deduplicate without this happening? Thanks.