i've never buy a variety box of D&D before, so correct me if i wrong, but
Fulton's Chinatown: 2 colors
Arristocrat: 2 colors
Arrco Tahoe: 2 colors
Monarch: 3 colors
so the total of variation would be 2*2*2*3 = 24 variations, how could be 144
It's simpler than you think it is.
There are 144 boxes. They do not insure your choice of colors, or any particular pattern of choices, for those decks that have more than one color - that's all. It's entirely possible that some of the variations are repeated, as it is possible that some of the variations exist as a one-of-a-kind mix.
Monarchs have more than three colors:
"Gold": gold pattern on black background, only 144 exist, only 111 released.
Original: white on black.
Original (Modified): same colors, thinner border.
White: gold on white
Silver: black on white
Red: white on red
Gold is very unlikely to appear given its rarity, but the other colors are fair game - either totally common (Original, Original Modified, Silver and Red) or rare but not ridiculously so (White), much like the "Game of Death" edition of the Fulton's Chinatown deck. That is, if you take their description to heart about available colors. White are rare and aren't being sold right now, but T11 still has plenty for contest prizes and other promotions, and the Bucks are on good terms with T11.