Silence repeated signer warning (#18162)

crates/sui-core/src/checkpoints/mod.rs

@@ -48,7 +48,7 @@ use sui_types::committee::StakeUnit;
 use sui_types::crypto::AuthorityStrongQuorumSignInfo;
 use sui_types::digests::{CheckpointContentsDigest, CheckpointDigest};
 use sui_types::effects::{TransactionEffects, TransactionEffectsAPI};
-use sui_types::error::SuiResult;
+use sui_types::error::{SuiError, SuiResult};
 use sui_types::gas::GasCostSummary;
 use sui_types::message_envelope::Message;
 use sui_types::messages_checkpoint::{
@@ -1919,6 +1919,14 @@ impl CheckpointSignatureAggregator {
         let envelope =
             SignedCheckpointSummary::new_from_data_and_sig(self.summary.clone(), signature);
         match self.signatures_by_digest.insert(their_digest, envelope) {
+            // ignore repeated signatures
+            InsertResult::Failed {
+                error:
+                    SuiError::StakeAggregatorRepeatedSigner {
+                        conflicting_sig: false,
+                        ..
+                    },
+            } => Err(()),
             InsertResult::Failed { error } => {
                 warn!(
                     checkpoint_seq = self.summary.sequence_number,