The tests are not that accurate.
Even on the same blood sample, different labs can often show very different results (commonly different labs will disagree by 25-30% when testing the same sample; even the same lab will get different results when running the same sample twice). Also, a variation of 140 points from day to day (as in your tests, even if they were taken at the same time of day) is very much within the normal variability. Men just don't have the same levels every day.
...assays measuring the same patient sample can give profoundly different
results. Furthermore, these differences are not consistent and
frequently increase with decreasing testosterone concentrations;