for the longest time i kept two gauges, rain specifically. Sometimes they'd be way off, i mean like waaaay off. I then was frustrated so i bought like 3 manual gauges and just randomly stuck them around the back yard. Waited on the afternoon storms (which is almost daily here in the summer, so it made the experiments easier), and over the course 3 days or so, i notices sometimes they were close, sometimes waaaaay off. Now three of my family members have a free rain gauge and i kept the one i had to begin with.
Someone in another forum i frequented at the time told me "A man with two watches never knows the correct time".