DUAL Refers To The Fans, Not The Slots
While the ASUS DUAL Radeon RX 6600 sounds like a two slot card, it is more of a 2.5 slot card (243 x 134 x 49mm); what it does have are two fans with small hubs to allow for longer fan blades in the same footprint as other RX 6600 cards. The implementation is apparently not just for aesthetics, the card ran at 55C under load in TweakTown’s tests. It is powered by a single 8-pin PCIe connector and offers a single HDMI 2.1 along with a trio of DisplayPort 1.4 outputs.
The memory runs at the usual 14Gbps while the GPU can be set to run either at 2491 MHz Boost Clock/2064 MHz Game Clock in OC Mode or 2491 MHz Boost/2044 MHz Game in Gaming mode, the only difference being the Game Clock in OC Mode. The performance reflects that, as it keeps pace with a reference RX 6600 but does not reliably surpass it.
The card does offer somewhat cooler running temperatures than the reference card and thus may also operate more quietly in many scenarios. The design of the card might appeal to you as well. Add this one to your list of watched cards, perhaps it will appear at or around MSRP some day.