Let's be a bit less strict here. (#6662)

This might actually happen in non malicious cases.

Co-authored-by: eskimor <eskimor@no-such-url.com>
(cherry picked from commit 5e0bcb0e)

polkadot/node/network/collator-protocol/src/error.rs

@@ -122,7 +122,7 @@ impl SecondingError {
 			PersistedValidationDataMismatch |
 				CandidateHashMismatch |
 				RelayParentMismatch |
-				Duplicate | ParentHeadDataMismatch |
+				ParentHeadDataMismatch |
 				InvalidCoreIndex(_, _) |
 				InvalidSessionIndex(_, _) |
 				InvalidReceiptVersion(_)