I would just let a monster act twice on one of the init cards.
An alternative is to use a suit from a normal deck of cards, then you have 13 init cards.
A standard deck can be up to 54 - 2 jokers and 4 suits of 1-13.
In Hoyle (the standard reference ruleset for casual players¹ of a majority of American games), suit ordering has a standard: Jokers ★ > Spades ♠ > Hearts ♥ > Diamonds ♦ > Clubs ♣.. Excepting the jokers, this is a standard for Bridge.
For a few RPGs, most notably Savage Worlds and Deadlands, that suit order is followed within a given rank. So K♠, Q♠, 4♦ K♦ would order as K♠,K♦ Q♠, 4♦.
To be honest, I've found myself routinely needing 11 or 12, but seldom more, in T2K and Alien, So I broke out the drawing program, made a 12 card 2.5" (~63.5mm) square cards (4×3 grid), printing them on 110# (200gsm) card, laminating with clear shelf-liner, then cutting them out.. One could also use business card stock, but I don't recommend it with laser printers for cards to play with - Laser printer toner does not deeply saturate, but ink jet does. Since my printers are all lasers, lamination assures the survival of the print during shuffling, but does alter the way they shuffle. Clear package sealing tape is also a viable option, if one gets it wide enough, and usually thinner than lamination sheet or clear shelf liner.
¹ it's worth noting that many competitive/tournament games in Hoyle have official rulesets that are slightly different from Hoyle's presentation, so it's seldom used in formal tournament play. Especially Bridge and Cribbage.