Dual band wifi range extender ( also called wifi signal booster) can boost both 2.4ghz wifi & 5ghz wifi signals from original source. OR you can connect to original 2.4ghz signal and extend wifi range to 5ghz network OR vice versa that is connect using 5ghz wifi and extend signal to 2.4ghz wifi network.
Dual Band wifi signal booster are a little costlier than single band wifi booster. Here is the list of Dual Band Wifi Boosters/Range Extenders available in India ……
Tp-Link AC750 RE200 Signal Booster more info
TP-Link Ac1750 Range Extender RE450 more info
Tp-Link AC1200 Dual Band Repeater RE300 more info
Tenda A18 AC1200 Wifi Extender with Gigabit port more info
Tp-Link AC1200 Wifi Extender RE305 more info
Netgear AC1750 wifi booster EX6250 more info
Netgear AC1200 wifi repeater EX6110 more info
Single Band wifi range extenders just for comparison.