You should always have at least three and preferably an odd number of similar sensors so that you can get at least a vague idea of consensus. The British Royal Navy rule was: take one chronometer or three, never two because with two you will always be unsure which one is correct while with three you can, usually, just average the two that are closest together and regard the third as an outlier.

See also https://blog.ipspace.net/2017/01/never-take-two-chronometers...