Another strange importing error

Here we go again with my CSV importing errors, we imported a file that was not correct and now when I try to re-import I get:

"The product is of the type but it already exists in the database and is of the type main. In order to avoid any problem the product insertion process has been skipped. Please correct its type before trying to reimport it."

I have deleted the old products with the same code but still get the message, the CSV looks as follows:

product_name;product_description;product_code;product_parent_id;product_weight;product_keywords;product_meta_description;price_value;storlek;images;categories;price_currency_id
Hollister T-shirt Dam;Hollister T-shirt Dam;447917;;1;Hollister Dam;Hollister Dam;149;m;447917.jpg;2,16,983,984,15,831,672,985,;150
;;447917 s;447917;;;;;s;;;
;;447917 m;447917;;;;;m;;;
;;447917 l;447917;;;;;l;;;

The problem apparently comes from one of your variants, not the main product. You must have a product with the code 447917 s or 447917 m or 447917 l in your database. But since you use that code as a variant in your CSV, it warns you that it's not ok.
You should first check on that.
Then you could add the column product_type in your CSV to force the type like that:
product_type;product_name;product_description;product_code;product_parent_id;product_weight;product_keywords;product_meta_description;price_value;storlek;images;categories;price_currency_id
main;Hollister T-shirt Dam;Hollister T-shirt Dam;447917;;1;Hollister Dam;Hollister Dam;149;m;447917.jpg;2,16,983,984,15,831,672,985,;150
variant;;;447917 s;447917;;;;;s;;;
variant;;;447917 m;447917;;;;;m;;;
variant;;;447917 l;447917;;;;;l;;;

I see the problem is that one of my co-workers imported a file with two colums "product_code" do we have to delete these in the DB? I can't find them in the back end.

Yes. You should try that.