If you’re listing them in the same [URL removed]

[[[URL removed]

with one mpn

If you have 2 listings that have the same MPN but are two different colors, list them in the same listing and for the attributes do them like this because like you say, the only difference is the color.

[[[URL removed]|black]] and then put the one MPN like this [[[URL removed]

But of course you’d replace the examples I gave with your own info.

I have not listed 2 almost identical listings in the same listing in a long time, so I’m not sure how within the listing we can make it clear that there are two different colors for the one listing (good idea to contact support unless someone already knows the answer for sure). But I do know that Google shopping’s rules do not want us to do two different listings for the same type of item when only having different variables such as color.

And then like said further above in other posts, if one item has 3 different colors within that one item, do it like this [[[URL removed] in the dominant order like MyTexasTreasures said.

From Google Merchant
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This defines the dominant color(s) for an item. When a single item has multiple colors, you can submit up to two additional values as accent [URL removed]

Combine the colors with ‘/’ in order of prominence (dominant color first, then at most two accent colors). For example, a black shoe with green accents should have a color value of ‘Black / Green’. In the case of non-deformable goods in Apparel like jewelry or wooden accessories where finishes or materials are equivalent to color, the finish or material name can be submitted in the color attribute (e.g., ‘Mahogany’ vs. ‘Stainless Steel’ vs. ‘Rose Gold’).
Limit the number of colors submitted to three values.