Yes, because this is the natural pattern of a virus, it is all about timing. The typical cycle of a virus is that a subject contracts the virus - a few days later the subject may display symptoms - the subject’s immune system kicks in and creates antibodies to fight the virus - the virus is destroyed. 

Timelines differ by person dependent on strength of immune system, and aggressiveness of infection.   Covid-19 tests are designed to detect the presence or the Covid-19 virus in the subject’s system. 

In the immediate days of contracting the Covid-19 virus, the level of virus in the system may be so small that it is not detectable by any test, and this could lead to a negative result. 

After a person has contracted the virus, and their immune system has destroyed the infection, dead virus cells may still be present in the subject’s system and this may be detected by the test. Even though the subject has no active infection and is no longer contagious, the presence of dead Coronavirus cells may lead to occasional positive results until the body fully clears these cells.

In this way, an infected person may receive initially one result and then another over a small time period.