The boxes we made for Time Breaker, ChronoTrek, and the Pyramid Quartet games fit in the same display as all our other boxes (holding 2 decks side by side) but only four per display, so they're 1.5x taller than our regular boxes. Since this is such a handy size, we had some extras made without any printing. Note that the image is just to show the size of the box. It does NOT come with any cards.

It holds two 130-card decks comfortably (for a total of 260 cards). As you can see from the picture, it's more than tall enough for a Fluxx deck on each side (2x100 cards), but not quite tall enough for a Chrono deck per side (2x140 cards)

So it's a bit of a squeeze, but still doable for an UberChrono (two Chrono-sized decks), but it would comfortably fit, say, the combined TNG and TOS decks plus the Bridge Expansion.

There's no insert to keep the two decks separate, but it would be pretty easy to make something out of cardstock.