Easy2Sync always stores the last state of the files. This 'memory' can be deleted to reset the task into the state it had when it was created. This changes synchronization decisions.
Easy2Sync switches to its 'careful' mode and will not delete any files, but instead copy them from the other directory. This makes sense if you deleted one directory and want Easy2Sync to rebuild it from the other one.
After the next synchronization, the database is completely rebuilt.