I have the same error,
[2018-10-19 07:48:16.585] FC[343A]: Check fs duplicates, fp: \\?\E:\Path\Of\File.txt (1 0), suffix: \\?\E:\Path\Of\File.txt (1 0)
I have already renamed the file on both machines, still flooded by the same error
Resilio Sync is stuck and after quitting the process still lingers around in the task manager.
EDIT: OK I managed to "unstuck" it by the following steps:
1. disconnect the folder
2. quit resilio & kill process from task manager
3. start resilio and ensure that everything else synced again
4. delete .sync folder from the disconnected folder
5. rename the problematic file to different names on both machines ( I also renamed the parent folder, just to be sure=
6. reconnect the folder