Sorry for not responding.
The core engine that runs the playback is the same irrespective of how the playback is triggered. However, we have not come around to testing this problem yet. Our main test engineer is out for a week. We will try to reproduce this problem as soon as he is back. In the meanwhile some more info would also be useful for us to dig into this problem.
1. If you switch the main and the spare devices, does the problem still happen on the new main device?
2. Are you using playlists?
3. When you say redundant mode, do you use the synchronization feature provided by uTrack24?
4. If you could upload your song(s) that are clicking, and send us a link it would be very helpful. You can send the link to email@example.com
Thanks for the patience, and sorry for the delay.