The device is designed for only one USB connection at any given time, either using the bottom USB connector via a charging/communication cradle or the side USB-C connector.
Simultaneous connections via both bottom and side USB connections are not supported.
If you attempt to connect via both the bottom and side USB-C at the same time, the bottom USB host will establish the connection, and the side USB-C will not.
However, if the device is in a charge-only cradle via the bottom connector, the USB-C is still available for connection.