Is it normal that I get completely different frequency sets every time I run biofeedback scan?

There may be hundreds of frequencies which benefit your body. The scan returns the strongest detected at that time. Biofeedback measures the effects on the signal of all the tissue (cells) between the electrodes. Most of these cells will be healthy, but will still contribute to the result. Reducing the distance between the contacts so that more unhealthy tissue is passing the signal improves the results, since the ratio of bad over good cells is increased.

However, the overall response will largely report back the cells which change the signal the most. The body is constantly absorbing and exchanging energies, so a different result is to be expected. Steps can be taken to improve results, such as increasing the "Samples/Step" and the Threshold. This prevents false positives coming through. Twisting the TENS cable also helps, as less electrical noise will be absorbed in the environment.

For more details, please check the link:
https://www.spooky2.com/forums/viewtopic.php?f=5&t=9500