Selling Duplicates

[RileyBiscuit981_XBL]

I have two Paul Skenes world baseball classic cards and I can’t figure out to sell duplicate.

[Dolenz_PSN]

I believe that is a non-sellable card. He comes from the WBC showdown and I don't think you can repeat that so I am not sure how you ended up with 2

[sbchamps17_NSW]

You only do that showdown once unless you lose the first run