I had the same issue with [[Cauldron Familiar]]. I personally find the JMP common set symbol extremely ugly while the ELD uncommon set symbol looks nice. If I have to use the JMP version of a card, seeing that set symbol annoys me every time I look at it, to the point I'd consider not using a style if that's necessary. Fortunately, I think I managed to make that one work by manually adding ELD copies with no style and then applying the style, but favoriting the style would add JMP copies instead since it's newer.
That reminds me of a related problem, which is that I often have 4 copies of an older version of a card but 1-3 copies of a newer version. If the favorited style applies to both, the game adds as many copies of the new version as I have before filling in the rest with the old version, so if I want them all the same, I have to remove all the new copies and increase the quantity of the old copies to 4.