We can confirm that a Micro SD and USB 3.0 thumb drive can be plugged in simultaneously. Though when using your SD and Micro SD card at the same time, only one will be able to read at a time.
It is simply a hardware limitation that we have discovered with the Aperture M. Micro SD and thumb drive devices can be read at the same time, SD and thumb drive devices can be read at the same time as well. It will not be able to read Micro SD and SD at the same time.