Hi,
5GHz and 2.4GHz are simply different frequencies, each with its advantages and disadvantages. To get the best of both worlds, 5GHz offers higher throughput at a shorter distance, while 2.4GHz offers increased coverage and higher solid object penetration.
If you have high quality Wi-Fi client devices, it's best to use the same SSID for both bands so your clients will automatically roam to the band that suits their needs best.
If it is an Ideal WiFi network without any interference then it should not be problem to configure same SSID with both band's.