Since both your AP and your card support both bands, you are free to select whichever one you want. However, you cannot connect both bands simultaneously. WiFi just doesn't work that way.
If you configured the SSID for both the 2.4GHz and 5GHz bands to have the same name, your laptop would only see one SSID, and you would only have one entry to connect to. But you still wouldn't be connected to both bands. Your laptop would "decide" to use one frequency or the other.
Now I'll interject my personal preferences here by saying that I believe your setup is optimal. I prefer to have the 5GHz band on a different SSID because then I can always be 100% sure that the 5GHz band is the one I'm connected to, and I don't trust the decision-making algorithm to make the correct choice. I've seen my laptop use the 2.4GHz band at hotels and other public WiFi networks even when the 5GHz band is available -- probably because the 2.4GHz band appeared to have better signal strength.
The 2.4GHz band is very crowded in most areas, whereas the 5GHz band is pretty much wide open almost everywhere I go. Moderate signal strength that is interference-free is usually preferable to good signal strength on a crowded spectrum. I can verify that result in my own house.