When unlocking a Variant card that requires two games, do I have to play them consequtively?

Solution 1:

I took some time and found out that, no it is not necessary. As a test, I decided to try and unlock Freedom Six Tachyon:

Lose a game to Iron Legacy with regular Tachyon on the team. Then, defeat any villain with regular Tachyon and without a Legacy on the team. Fleet of Foot must be played at least 5 times.

To do this, I lost a game with Iron Legacy (not hard to do; just keep passing), then played a few games with Tachyon. Then I played one where I played Fleet of Foot 5 times and the variant unlocked.

I have no reason to think that it works differently for other variant unlocks (I'll unlock others to confirm), but so no, you do not have to play a game right away.