multiple products appearing in feed

hi
we have set up a feed and I think we are almost set but I just noticed there is mulitple products with the same ID/SKU see here: https://app.screencast.com/Y1jgtMKZYjgpa

we are using WooCommerce Product Options for an attribute, see here: https://app.screencast.com/Wgom3KNLgbsev
And we are using ‘Attributes’ but not for an option on the front end: https://app.screencast.com/9IITHZt0SOtLU

we have this purely so visitors can search for the ‘tartan’ on the front end see here: https://app.screencast.com/hF5Ooex2CTgM9

So in the feed I set filter to ‘exclude products iwth ‘pa_tartan’ but that has not worked. See here: https://app.screencast.com/l7PaNwdePZKXY

I have viewed the feed in a private browser as well.

I am wondering what I need to do to remove ‘two of the duplicate products’ or each product?

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