Several things.
Cost. The variable cost thing has been addressed already, so does not require reiteration.
Name. It is anything but fluid. First thing first, I'd drop "The." Wordplay can make it usable still. And with a word like Duo, you can just add a random letter. [e.g. Duox, Duon, etc.]
Abilities. For unupped, you can save space and just call the ability Parallel Universe. For upped, if you're starting at 0 Att, it would not hurt to at least lower the cost to 2
.
Upgrading. Personally, I wouldn't bother upgrading the card at all. The unupped has a much greater initial potential than the upped. And considering the average game, there's no way the upped will catch up to the unupped's progress efficiently. Also, as one target, the upgraded is more susceptible to creature control than the upgraded. In fact, Deja Vu is a much better card than the upgraded card.
My suggestions?
I'd set the initial playing cost somewhere between 6 and 10, depending on what the initial stats will be. There should be no need to regain quanta since there is too much tacked on as is. Switch the cards' unupped and upped abilities. And make both have medium stats like 3|3 or something. Ability costs can drop to, since you'll make up for it with card costs.