Create two sandboxes populated from the same module. In each sandbox, create a conflicting modification to one file. Check in the modified version from one sandbox. Update the other sandbox - note the conflict is reported. Update again - file now appears up-to-date, i.e. it is no longer reported modified, much less conflict'd.
Client: Concurrent Versions System (CVS) 1.12.13
Server: Concurrent Versions System (CVS) 1.11.2
Mandriva Linux 1007, 2.6.17-13