1. You can only use one set of tens pads on the body at one time.
Current can be additive within the body, which may cause damage within the body. Some frequencies are above what typically stimulates nerves or muscles, so one may not realize damage is occurring or has occurred until after the session is over. Just not a good practice.
Signal from one device may go to another and the result cause some malfunctions within the gear. While I think this would be rare, it could happen.
2. The issue with using two sets of TENS pads (meaning 4 individual pads) with Spooky generators is this creates a short-circuit to ground, and this causes the generator to not output anything, though the generators are not damaged.
If you had two battery-powered inverters, and plugged each Spooky generator into those generators, then there would be no common ground, and this would work.
With the HeaWea MicroGen, if you have two of them, since they run on batteries, there is no common ground, and this is safe.
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