core/txpool/blobpool: return ErrAlreadyKnown for duplicate txs

Signed-off-by: Lee Bousfield <ljbousfield@gmail.com>

core/txpool/blobpool/blobpool.go

@@ -1131,8 +1131,12 @@ func (p *BlobPool) validateTx(tx *types.Transaction) error {
 		next    = p.state.GetNonce(from)
 	)
 	if uint64(len(p.index[from])) > tx.Nonce()-next {
-		// Account can support the replacement, but the price bump must also be met
 		prev := p.index[from][int(tx.Nonce()-next)]
+		// Ensure the transaction is different than the one tracked locally
+		if prev.hash == tx.Hash() {
+			return txpool.ErrAlreadyKnown
+		}
+		// Account can support the replacement, but the price bump must also be met
 		switch {
 		case tx.GasFeeCapIntCmp(prev.execFeeCap.ToBig()) <= 0:
 			return fmt.Errorf("%w: new tx gas fee cap %v <= %v queued", txpool.ErrReplaceUnderpriced, tx.GasFeeCap(), prev.execFeeCap)

core/txpool/blobpool/blobpool_test.go

@@ -984,9 +984,14 @@ func TestAdd(t *testing.T) {
 				},
 			},
 			adds: []addtx{
-				{ // New account, 1 tx pending: reject replacement nonce 0 (ignore price for now)
+				{ // New account, 1 tx pending: reject duplicate nonce 0
 					from: "alice",
 					tx:   makeUnsignedTx(0, 1, 1, 1),
+					err:  txpool.ErrAlreadyKnown,
+				},
+				{ // New account, 1 tx pending: reject replacement nonce 0 (ignore price for now)
+					from: "alice",
+					tx:   makeUnsignedTx(0, 1, 1, 2),
 					err:  txpool.ErrReplaceUnderpriced,
 				},
 				{ // New account, 1 tx pending: accept nonce 1
@@ -1009,10 +1014,10 @@ func TestAdd(t *testing.T) {
 					tx:   makeUnsignedTx(3, 1, 1, 1),
 					err:  nil,
 				},
-				{ // Old account, 1 tx in chain, 1 tx pending: reject replacement nonce 1 (ignore price for now)
+				{ // Old account, 1 tx in chain, 1 tx pending: reject duplicate nonce 1
 					from: "bob",
 					tx:   makeUnsignedTx(1, 1, 1, 1),
-					err:  txpool.ErrReplaceUnderpriced,
+					err:  txpool.ErrAlreadyKnown,
 				},
 				{ // Old account, 1 tx in chain, 1 tx pending: accept nonce 2 (ignore price for now)
 					from: "bob",