I've seen players handle this in a few ways, either by accepting the situation, coming up with alternative colour or sculpts, or by simply numbering their bases.
When I first got into Seamus I went Belle mad, buying two clamshells of belles giving me duplicate sculpts. Armed with these I really had no choice but to look at alternative colour schemes but in my mind there was no point changing the colours of my mini, if the card didn't correspond as well and so I asked Mr Neverborn, with his significant photoshop experience, to do me up some replacement cards. Since then I've gone on to learn art packages myself, which will turn out to be something of a mixed blessing. I have a few duplicates sculpts in my Kirai crew that I want to come up with alternative colour schemes for, and I also want to turn 2 beckoners into dead doxies for Brawls.
What follows then are some scans of the photoshopped cards so that you might use them yourselves if you find yourself with some duplicate sculpts, or maybe you're looking for some inspiration.
It's funny as these took to the board they developed personalities and are now affectionately known as Miss Peaches, Miss Bluebell and Miss Lemons (or Bananas as Mr Neverborn will insist on calling her)
Miss Lemon - notice how she gets picked on....
More to follow in the coming weeks as Kirai and crew get some photoshop love and I'll share the files next time, I just don't have the files Mr Neverborn did for me.