Tested with c.nc.com version 23.0.0.10

Have a two folders with the same file:

• /A/B/test.txt
• /A/C/test.txt

Try to copy /A/B/test.txt to /A/C from the web interface ("move or copy" operation in the "..."-menu)

Result

Error message is show: Could not copy "test.txt", target exists

Expected

Show the conflict dialog and allow the user to chose which version they want to keep, same as we show during upload of files with the same filename.