EX6150/ One Wifi Name set up

I just purchased and set up  my EX6150v2. Updating to the latest firmware gives me the options to enable "Smart Roaming" and "One WIFI Name". When I check both these items, and after the 6150 finishes configuration, the options come back with only "Smart Roaming" checked. Is this because the current router that I am using shows two SSID's, one for the 2ghz band and one for the 5ghz band. The SSID's only differ by the included "2ghz" or "5ghz" part of the SSID. Do I need to change the router settings to have the same SSID for both bands?  How will this affect devices that only can connect to the 2ghz band?