Greg (@navytech), Yes you can connect 2 different devices concurrently to a PostCard for example. I sometimes use a smartphone over BLE and an android tablet over SPP (Bluetooth Classic) at the same time for specific testing scenarios - but this isn’t a normal/typical operation for me. I can’t promise the TX2 is the same, but I would guess so since it’s also Dual Mode Bluetooth.
For normal operation however, I let the smartphone handle sending the NTRIP corrections (SW Maps as an example) and receive the NMEA Output, both over the same BLE connection from the phone. The RTK Everywhere Firmware does a great job with multiple bluetooth characteristics to handle the bidirectional data and RTCM priority.