so we need to find someone with access to 2 identical watches, perhaps someone who bought some for the whole family? instead of strapping all to the same arm, j

so we need to find someone with access to 2 identical watches, perhaps someone who bought some for the whole family? instead of strapping all to the same arm, just strap one on each wrist (assume the "left" heart's rate is approximately equal to "the heart on the right"). Are we claiming that every product needs 2 FDA applications: one for the end user and one for a special run of demo watches? I believe (but did not check) that demo watches would be either exempt or go unnoticed considering the amount of data it could gather...