When I own a card, its Gold number and the quantity I own are indicated.
If the quantity (the second number, after the "x") is greater than 1, then the card is available for trade.
I'm looking in priority for cards I don't own at all, whatever Gold value on the back. But I'm willing to get also cards I already have but with a different Gold value.
Also, all cards don't have the same back, but it's not my priority to get all cards with all backs!
For the differents backs, see
Ref. 3-01 : BR - Black orcs of the Conqueror
Ref. 3-02 : LC - Saerith, bride of Haasek
Ref. 3-03 : DW - Thorgrim's steel hammers
Ref. 3-03 : DW - High king Thorgrim
Ref. 3-03 : DW - Thorgrim's grim-axes
Ref. 3-04 : DW - Hellbrandt Grimm
Ref. 3-06 : WA/BD - Fight as one
Ref. 3-05 : WH/WA-The silver serpent sheds its skin