Unfortunately, there is no such tool.
But… even if there were such a tool it is nearly impossible to know which system ID is associated with which physical device since motherboards normally route USB through the USB hub and device ports are assigned dynamically. So at most you will be able to understand if just one device is in use or both devices are used.
And well, there is non-programmatic solution - "kitchen sink method" - you can simply touch your devices – the hotter device is the higher the usage is !
Hope it helps.