Little info but assumptions being made. Yes, two duplex/double switches can be wired, so it would become a 2-gang box. The 4-gang box would need to be swapped out and sized with depth that allows adequate cable fill. The reason for swapping the box is the assumption is you want to move the switches as far as you can to one side, so if you were to use a 2-gang mud ring on the existing box (even if an option on your style of box), it would center the gangs on the 4-gang box not giving enough room. And also if you have the room and cable slack the box may be able to be moved to the other side of the stud.

We have a Crestron system, so doesn't quite apply to standard wiring, but solutions are out there, even thought you might not have seen it yourself.

Go to an electric supply house and not just the HD/Lowes electric isle!

Controls 5+ lights or groups (includes dimmer)

Are there 3-way switches in the existing box? I have not seen a duplex 3-way switch.

stacking is fine.

Have it configured vertically instead of horizontally.