Does Clockify have a feature or at least have a warning that indicates if you have logged an overlapping time? Whether it is on the same task or different task.
Clockify does allow overlapping entries and there is no option to disable it.
If it did not allow overlapping, the system would have to prevent the user from adding time if there is already some time tracked in that period or it would have to automatically deal with overlapping time.
For technical and optimization reasons, there are no plans to prevent overlapping time.
However, if you have entries with overlapping start and end times, it is possible to find them in Excel or Google Sheets. You can see more about it here.