From c12b2a3ae68289d0e8b671a92555ce89eb67e010 Mon Sep 17 00:00:00 2001
From: Mithril Man <red.angel@libero.it>
Date: Fri, 31 Jul 2020 01:47:17 +0200
Subject: [PATCH] fixes #197

---
 .../Rules/CommonRules/CheckPowTransactionRule.cs              | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/src/Features/Blockcore.Features.Consensus/Rules/CommonRules/CheckPowTransactionRule.cs b/src/Features/Blockcore.Features.Consensus/Rules/CommonRules/CheckPowTransactionRule.cs
index e72a37df0..5cc444ec4 100644
--- a/src/Features/Blockcore.Features.Consensus/Rules/CommonRules/CheckPowTransactionRule.cs
+++ b/src/Features/Blockcore.Features.Consensus/Rules/CommonRules/CheckPowTransactionRule.cs
@@ -86,13 +86,11 @@ public virtual void CheckTransaction(Network network, ConsensusOptions options,
             var inOutPoints = new HashSet<OutPoint>();
             foreach (TxIn txin in tx.Inputs)
             {
-                if (inOutPoints.Contains(txin.PrevOut))
+                if (!inOutPoints.Add(txin.PrevOut))
                 {
                     this.Logger.LogTrace("(-)[TX_DUP_INPUTS]");
                     ConsensusErrors.BadTransactionDuplicateInputs.Throw();
                 }
-
-                inOutPoints.Add(txin.PrevOut);
             }
 
             if (tx.IsCoinBase)