Yesterday we canceled a batch of WUs "gone bad" because of the blackout. Mostly were unsent or aborted, but a few managed to start nevertheless, and were therefore canceled while running. (This was however irrespective to their redundancy.)
Some background: "Cancellation" is an exceptional measure taken to fix server problems. It kills running jobs, and of course we only use it in emergency (as yesterday). It is not related to the redundancy of WUs.
"Redundant result", "not needed" or similar, are "gentle" cancellation mechanisms which are part of the normal workflow of BOINC: they respect running jobs, so you don't lose credit.
Confusingly, both events generate "exit code -221". To tell one from the other one has to look at the "claimed credit" column (I believe), which is zero for the "gently cancelled" ones.