Not if they were tested with PCR. PCR can have false negative, but false positive is extremely unlikely.
Given the (currently) very low numbers of these "apparently relapsed" cases versus the total recovered cases, I think it is most likely.
- Similar sympthoms but different disease (flu?)
- False negatives, and so people were still actually sick
In addition, I wonder if those patients had distinct clinical features compared to others. In absence of more data (and these cases are very uncommon) it is hard to tell.
Probably a good idea would be to do a study with periodical follow up of a large cohort of discharged patients. This would probably give better indication.