Import by cardlist doesn't auto-combine copies of same card

When adding cards to inventory, if I use the "Import -> Card List" feature (I suspect it also applies to automatically adding cards from trade to inventory), deckbox won't combine a newly added card with the copies of the same card already in the inventory, even if they have the same set specified, and no language or condition information.

For an example, look at the card Conjured Currency in my current inventory.