They are most likely not reinfections. You can still have the virus reproducing in your body, yet have recovered and are no longer spreading it. If you’re in this post-infection period, you’ll still intermittently test positive (especially when your stool is sampled). This is similar to EBV or HIV.

These tests (RT-PCR) also aren’t sensitive enough to test whether the virus is alive or dead, they test for the presence of genetic material.