I hate to tell you but your left hand may have diabetes.
In all seriousness, there is always going to be a margin of error in testing. Dirty or wet hands can affect readings and there's always going to be varied readings from the monitor itself even when everything else is the same.
I own 6 different glucose monitors (plus my dexcom). If I tested using all 6, I'd be surprised if any two read exactly the same.
Best thing you can do is test in the same conditions as best as possible. Hands should be clean, and dry (including if you use alcohol pads)