If I press the "import deck to arena" logo button next to decklists on certain sites, including wizards, there is unwanted behavior regarding what copies the game chooses to import. I severely doubt this is intended by the decklist makers and always happens.

If I for example in my case import a deck that has 4 fabled passage in it,
it uses 1 M21 one that I have and 3 eldraine ones, creating two lines on the deck list on the right, even if I have 4 ELD fabled passages it should start with.
Same happens with Llanowar Elves, I have 4 of the special dominaria versions and 2 of the normal dominaria versions, and I get a mix of those.

This is not a big issue as such, but most people would almost certainly want it to be other way than having two lines for same card.