Superhub 2 supports both 2.4GHz and 5GHz wifi operation independently at the same time. For example, I can let my Sony Xperia M2 use 5GHz wifi while other devices like my ZTE Blade III use 2.4GHz. I found this by trial and error using Superhub2 web interface and the Fing application for the Xperia and Blade III. The manuals of the Xperia and Blade iii did not specify if the devices could operate at 5GHz as far as I could see.
For Blade III in
http://www.gsmarena.com/zte_blade_iii-4983.php WLAN section says: Wi-Fi 802.11 b/g/n, Wi-Fi Direct, Wi-Fi hotspot, DLNA
and for Sony Xperia M2 in
http://www.gsmarena.com/sony_xperia_m2-6146.php WLAN section says: Wi-Fi 802.11 a/b/g/n, dual-band, Wi-Fi Direct, DLNA, Wi-Fi hotspot.
I observed that Blade III does not work at 5GHz but the Xperia does. The only difference between the two WLAN specs is the 'dual-band' phrase for Xperia, so I tentatively assumed this is the keyphrase that specifies that a device can handle dual bands. Then here is a (probably incomplete) list of dual-band devices from gsmareana:
Google Nexus
Samsung Galaxy, S3, s4 and S5
HTC one M8, HTC remix
Iphone 5s and Iphone 6
Lenovo k900, X2, Z2, Z2-Pro
LG G2, G3
Motorola Moto X, Droid-ultra
Sony Xperia T3, Z1,Z2 and Z3
Xiaomi Note 4G, Mi 3
ZTE Nubia7/6/5, Grand IIs, Grand Memo II LTE, Star 1,
Most fairly expensive devices.
I am confused by the notation Wi-Fi 802.11 b/g/n in gsmarena because it includes wifi standard 802.11n. According to Wifi standards/IEEE 802.11 - Wiki.html#802.11-2007, standard 802.11n should handle both 2.4GHz and 5GHz bands but Blade III certainly does not. So is the 'dual-band' keyphrase in gsmareana equivalent to wifi standard 802.11n or the more recent 802.11ac? or have I completely misunderstood this?
Q1. are there other notations in common use that specfy that a device can handle dual band?
or is there some other way of finding out except buying a device and try it?