The badges on the back are different and indicator these cars serve difference purposes. My guess - the red one is the model S plaid mule and the blue is a mule for the roadster. Great way to get data and with agile methodology incremental versions of the production cars. 


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Tesla Model S P100D & Model X P90D & 2016 BMW i8 & 2017 Sept 991.2 GT3 ordered. 2020 Porsche Mission E on order