so regarding your results with a single sensor, I would suggest you to save your project (File->saveProject ) after scanning, such that you can reload it and play with the settings.
Your images look like the keyframe selection for retexturing is not optimal, such that you have to reselect the keyframes manually. In order to do so, go to Keyframes and step for each Camera through the corresponding frames. With the checkbox unselect the frames that are showing the face, only keep a reduced number of frames for the face(maybe one front and the other two from the side). Then rerun the retexturing. This should remove such artifacts like the one which can be seen in the face.
In general you can play arround with the keyframes used for retexturing and unselect them as you like to optimize your texture.
For the multisensor setup the very same problem might have appeared. Try to play arround here with the re-texturing as well. A further problem might be that the person could have moved the arms slightly in the multisensor setup, such that such artifacts appeared. So make sure the person is not moving during scanning.
I hope this might help to improve your texturing results.