[atlas] Discrepancy between built-in test and my own test

Hi, I have a probe (probe ID 1005229) running on a VM in the Oracle Cloud. On that probe I have a ping test (measurement ID 85299016) to Google. Thus, an Atlas controller instructs my probe to do a latency test every 5 minutes. The result of that test is fairly consistent at around 7 ms. However, there is also a built-in measurement running on all Atlas probes to Google, every probe automatically performs this measurement every 10 minutes. The results of that test is fairly consistent at around 1 ms. Why is there such a difference between these two equal measurements? Both to Google, both from the same probe. Any clues? Regards, Ernst J. Oud