diff --git a/crates/rpc/rpc/src/eth/error.rs b/crates/rpc/rpc/src/eth/error.rs
index fbaa91698..e8c0c0c7a 100644
--- a/crates/rpc/rpc/src/eth/error.rs
+++ b/crates/rpc/rpc/src/eth/error.rs
@@ -346,6 +346,7 @@ impl From<PoolError> for RpcPoolError {
             PoolError::DiscardedOnInsert(_) => RpcPoolError::TxPoolOverflow,
             PoolError::InvalidTransaction(_, err) => err.into(),
             PoolError::Other(_, err) => RpcPoolError::Other(err),
+            PoolError::AlreadyImported(_) => RpcPoolError::AlreadyKnown,
         }
     }
 }
diff --git a/crates/transaction-pool/src/error.rs b/crates/transaction-pool/src/error.rs
index 82b5832eb..be74f9986 100644
--- a/crates/transaction-pool/src/error.rs
+++ b/crates/transaction-pool/src/error.rs
@@ -8,6 +8,9 @@ pub type PoolResult<T> = Result<T, PoolError>;
 /// All errors the Transaction pool can throw.
 #[derive(Debug, thiserror::Error)]
 pub enum PoolError {
+    /// Same transaction already imported
+    #[error("[{0:?}] Already imported")]
+    AlreadyImported(TxHash),
     /// Thrown if a replacement transaction's gas price is below the already imported transaction
     #[error("[{0:?}]: insufficient gas price to replace existing transaction.")]
     ReplacementUnderpriced(TxHash),
@@ -36,6 +39,7 @@ impl PoolError {
     /// Returns the hash of the transaction that resulted in this error.
     pub fn hash(&self) -> &TxHash {
         match self {
+            PoolError::AlreadyImported(hash) => hash,
             PoolError::ReplacementUnderpriced(hash) => hash,
             PoolError::FeeCapBelowMinimumProtocolFeeCap(hash, _) => hash,
             PoolError::SpammerExceededCapacity(_, hash) => hash,
@@ -60,6 +64,10 @@ impl PoolError {
     #[inline]
     pub fn is_bad_transaction(&self) -> bool {
         match self {
+            PoolError::AlreadyImported(_) => {
+                // already imported but not bad
+                false
+            }
             PoolError::ReplacementUnderpriced(_) => {
                 // already imported but not bad
                 false
diff --git a/crates/transaction-pool/src/lib.rs b/crates/transaction-pool/src/lib.rs
index dd65c6f72..8807d5e29 100644
--- a/crates/transaction-pool/src/lib.rs
+++ b/crates/transaction-pool/src/lib.rs
@@ -279,14 +279,14 @@ where
         self.pool.pooled_transactions_hashes()
     }
 
-    fn pooled_transactions(&self) -> Vec<Arc<ValidPoolTransaction<Self::Transaction>>> {
-        self.pool.pooled_transactions()
-    }
-
     fn pooled_transaction_hashes_max(&self, max: usize) -> Vec<TxHash> {
         self.pooled_transaction_hashes().into_iter().take(max).collect()
     }
 
+    fn pooled_transactions(&self) -> Vec<Arc<ValidPoolTransaction<Self::Transaction>>> {
+        self.pool.pooled_transactions()
+    }
+
     fn pooled_transactions_max(
         &self,
         max: usize,
diff --git a/crates/transaction-pool/src/pool/txpool.rs b/crates/transaction-pool/src/pool/txpool.rs
index ddaafb769..79e87d9b2 100644
--- a/crates/transaction-pool/src/pool/txpool.rs
+++ b/crates/transaction-pool/src/pool/txpool.rs
@@ -214,6 +214,10 @@ impl<T: TransactionOrdering> TxPool<T> {
         on_chain_balance: U256,
         on_chain_nonce: u64,
     ) -> PoolResult<AddedTransaction<T::Transaction>> {
+        if self.contains(tx.hash()) {
+            return Err(PoolError::AlreadyImported(*tx.hash()))
+        }
+
         // Update sender info with balance and nonce
         self.sender_info
             .entry(tx.sender_id())
@@ -1146,7 +1150,7 @@ impl SenderInfo {
 mod tests {
     use super::*;
     use crate::{
-        test_utils::{MockTransaction, MockTransactionFactory},
+        test_utils::{MockOrdering, MockTransaction, MockTransactionFactory},
         traits::TransactionOrigin,
     };
 
@@ -1213,6 +1217,21 @@ mod tests {
         assert!(inserted.state.intersects(expected_state));
     }
 
+    #[test]
+    fn insert_already_imported() {
+        let on_chain_balance = U256::ZERO;
+        let on_chain_nonce = 0;
+        let mut f = MockTransactionFactory::default();
+        let mut pool = TxPool::new(MockOrdering::default(), Default::default());
+        let tx = MockTransaction::eip1559().inc_price().inc_limit();
+        let tx = f.validated(tx);
+        pool.add_transaction(tx.clone(), on_chain_balance, on_chain_nonce).unwrap();
+        match pool.add_transaction(tx, on_chain_balance, on_chain_nonce).unwrap_err() {
+            PoolError::AlreadyImported(_) => {}
+            _ => unreachable!(),
+        }
+    }
+
     #[test]
     fn insert_replace() {
         let on_chain_balance = U256::ZERO;