Temporary training mode: no. Permanent pairing for training: yes!
When we are paired for temporary training (2 headsets paired to the same base) you will be locked in the mode (computer or phone) you were in when you started the process.
To change modes, you will need to turn off the primary headset, move to the other mode, then do the secondary pairing process again.
However, you can do permanent pair, which will allow you to switch modes at will!