It does not. The issue of duplicate test reports is beyond the scope of CPAN::Reporter. All CPAN::Reporter does is interface CPAN.pm to Test::Reporter.

If you do not want to send test reports, you can easily disable it with "o conf test_report 0" from the CPAN shell prompt. To make that permanent, use "o conf commit". No CPAN::Reporter configuration is lost, so you can re-enable at any time with "o conf test_report 1".