I have a use case where I need to determine whether two MAC addresses belong to the same router with dual band connection 2.4 GHz ad 5 GHz.  

When I did some study, I found that the MAC address of all WiFi AP serving 2.4 GHz and that of 5 GHz differ only by 2 in their last digits.  

Example:  
> 2.4 GHz MAC: aa:bb:cc:dd:ee:53   
5 GHz MAC: aa:bb:cc:dd:ee:55

 
So is there any standard for dual band routers, that makes them follow this rule ?
Also If not this, is there any other way I can know whether the two MAC addresses are of the same router, but with different bands.