diff --git a/src/psbt.h b/src/psbt.h
index 5ec806d14ee392..c288ec1a86821e 100644
--- a/src/psbt.h
+++ b/src/psbt.h
@@ -101,6 +101,9 @@ struct PSBTInput
 
     template <typename Stream>
     inline void Unserialize(Stream& s) {
+        // Used for duplicate key detection
+        std::set<std::vector<unsigned char>> key_lookup;
+
         // Read loop
         bool found_sep = false;
         while(!s.empty()) {
@@ -121,7 +124,7 @@ struct PSBTInput
             // Do stuff based on type
             switch(type) {
                 case PSBT_IN_NON_WITNESS_UTXO:
-                    if (non_witness_utxo) {
+                    if (!key_lookup.emplace(key).second) {
                         throw std::ios_base::failure("Duplicate Key, input non-witness utxo already provided");
                     } else if (key.size() != 1) {
                         throw std::ios_base::failure("Non-witness utxo key is more than one byte type");
@@ -152,7 +155,7 @@ struct PSBTInput
                     break;
                 }
                 case PSBT_IN_SIGHASH:
-                    if (sighash_type > 0) {
+                    if (!key_lookup.emplace(key).second) {
                         throw std::ios_base::failure("Duplicate Key, input sighash type already provided");
                     } else if (key.size() != 1) {
                         throw std::ios_base::failure("Sighash type key is more than one byte type");
@@ -161,7 +164,7 @@ struct PSBTInput
                     break;
                 case PSBT_IN_REDEEMSCRIPT:
                 {
-                    if (!redeem_script.empty()) {
+                    if (!key_lookup.emplace(key).second) {
                         throw std::ios_base::failure("Duplicate Key, input redeemScript already provided");
                     } else if (key.size() != 1) {
                         throw std::ios_base::failure("Input redeemScript key is more than one byte type");
@@ -176,7 +179,7 @@ struct PSBTInput
                 }
                 case PSBT_IN_SCRIPTSIG:
                 {
-                    if (!final_script_sig.empty()) {
+                    if (!key_lookup.emplace(key).second) {
                         throw std::ios_base::failure("Duplicate Key, input final scriptSig already provided");
                     } else if (key.size() != 1) {
                         throw std::ios_base::failure("Final scriptSig key is more than one byte type");
@@ -245,6 +248,9 @@ struct PSBTOutput
 
     template <typename Stream>
     inline void Unserialize(Stream& s) {
+        // Used for duplicate key detection
+        std::set<std::vector<unsigned char>> key_lookup;
+
         // Read loop
         bool found_sep = false;
         while(!s.empty()) {
@@ -266,7 +272,7 @@ struct PSBTOutput
             switch(type) {
                 case PSBT_OUT_REDEEMSCRIPT:
                 {
-                    if (!redeem_script.empty()) {
+                    if (!key_lookup.emplace(key).second) {
                         throw std::ios_base::failure("Duplicate Key, output redeemScript already provided");
                     } else if (key.size() != 1) {
                         throw std::ios_base::failure("Output redeemScript key is more than one byte type");
@@ -373,6 +379,9 @@ struct PartiallySignedTransaction
             throw std::ios_base::failure("Invalid PSBT magic bytes");
         }
 
+        // Used for duplicate key detection
+        std::set<std::vector<unsigned char>> key_lookup;
+
         // Read global data
         bool found_sep = false;
         while(!s.empty()) {
@@ -394,7 +403,7 @@ struct PartiallySignedTransaction
             switch(type) {
                 case PSBT_GLOBAL_UNSIGNED_TX:
                 {
-                    if (tx) {
+                    if (!key_lookup.emplace(key).second) {
                         throw std::ios_base::failure("Duplicate Key, unsigned tx already provided");
                     } else if (key.size() != 1) {
                         throw std::ios_base::failure("Global unsigned tx key is more than one byte type");
diff --git a/test/functional/data/rpc_psbt.json b/test/functional/data/rpc_psbt.json
index b2683d82b071fe..d831d225b782a1 100644
--- a/test/functional/data/rpc_psbt.json
+++ b/test/functional/data/rpc_psbt.json
@@ -17,7 +17,15 @@
         "cHNidP8BAHMCAAAAATAa6YblFqHsisW0vGVz0y+DtGXiOtdhZ9aLOOcwtNvbAAAAAAD/////AnR7AQAAAAAAF6kUA6oXrogrXQ1Usl1jEE5P/s57nqKHYEOZOwAAAAAXqRS5IbG6b3IuS/qDtlV6MTmYakLsg4cAAAAAAAEBHwDKmjsAAAAAFgAU0tlLZK4IWH7vyO6xh8YB6Tn5A3wCAwABAAAAAAEAFgAUYunpgv/zTdgjlhAxawkM0qO3R8sAAQAiACCHa62DLx0WgBXtQSMqnqZaGBXZ7xPA74dZ9ktbKyeKZQEBJVEhA7fOI6AcW0vwCmQlN836uzFbZoMyhnR471EwnSvVf4qHUa4A",
         "cHNidP8BAHMCAAAAATAa6YblFqHsisW0vGVz0y+DtGXiOtdhZ9aLOOcwtNvbAAAAAAD/////AnR7AQAAAAAAF6kUA6oXrogrXQ1Usl1jEE5P/s57nqKHYEOZOwAAAAAXqRS5IbG6b3IuS/qDtlV6MTmYakLsg4cAAAAAAAEBHwDKmjsAAAAAFgAU0tlLZK4IWH7vyO6xh8YB6Tn5A3wAAgAAFgAUYunpgv/zTdgjlhAxawkM0qO3R8sAAQAiACCHa62DLx0WgBXtQSMqnqZaGBXZ7xPA74dZ9ktbKyeKZQEBJVEhA7fOI6AcW0vwCmQlN836uzFbZoMyhnR471EwnSvVf4qHUa4A",
         "cHNidP8BAHMCAAAAATAa6YblFqHsisW0vGVz0y+DtGXiOtdhZ9aLOOcwtNvbAAAAAAD/////AnR7AQAAAAAAF6kUA6oXrogrXQ1Usl1jEE5P/s57nqKHYEOZOwAAAAAXqRS5IbG6b3IuS/qDtlV6MTmYakLsg4cAAAAAAAEBHwDKmjsAAAAAFgAU0tlLZK4IWH7vyO6xh8YB6Tn5A3wAAQAWABRi6emC//NN2COWEDFrCQzSo7dHywABACIAIIdrrYMvHRaAFe1BIyqeploYFdnvE8Dvh1n2S1srJ4plIQEAJVEhA7fOI6AcW0vwCmQlN836uzFbZoMyhnR471EwnSvVf4qHUa4A",
-        "cHNidP8BAHMCAAAAAbiWoY6pOQepFsEGhUPXaulX9rvye2NH+NrdlAHg+WgpAQAAAAD/////AkBLTAAAAAAAF6kUqWwXCcLM5BN2zoNqMNT5qMlIi7+HQEtMAAAAAAAXqRSVF/in2XNxAlN1OSxkyp0z+Wtg2YcAAAAAAAEBIBNssgAAAAAAF6kUamsvautR8hRlMRY6OKNTx03DK96HAQcXFgAUo8u1LWpHprjt/uENAwBpGZD0UH0BCGsCRzBEAiAONfH3DYiw67ZbylrsxCF/XXpVwyWBRgofyRbPslzvwgIgIKCsWw5sHSIPh1icNvcVLZLHWj6NA7Dk+4Os2pOnMbQBIQPGStfYHPtyhpV7zIWtn0Q4GXv5gK1zy/tnJ+cBXu4iiwABABYAFMwmJQEz+HDpBEEabxJ5PogPsqZRAAEAFgAUyCrGc3h3FYCmiIspbv2pSTKZ5jU"
+        "cHNidP8BAHMCAAAAAbiWoY6pOQepFsEGhUPXaulX9rvye2NH+NrdlAHg+WgpAQAAAAD/////AkBLTAAAAAAAF6kUqWwXCcLM5BN2zoNqMNT5qMlIi7+HQEtMAAAAAAAXqRSVF/in2XNxAlN1OSxkyp0z+Wtg2YcAAAAAAAEBIBNssgAAAAAAF6kUamsvautR8hRlMRY6OKNTx03DK96HAQcXFgAUo8u1LWpHprjt/uENAwBpGZD0UH0BCGsCRzBEAiAONfH3DYiw67ZbylrsxCF/XXpVwyWBRgofyRbPslzvwgIgIKCsWw5sHSIPh1icNvcVLZLHWj6NA7Dk+4Os2pOnMbQBIQPGStfYHPtyhpV7zIWtn0Q4GXv5gK1zy/tnJ+cBXu4iiwABABYAFMwmJQEz+HDpBEEabxJ5PogPsqZRAAEAFgAUyCrGc3h3FYCmiIspbv2pSTKZ5jU",
+        "cHNidP8BACoCAAAAAAFAQg8AAAAAABepFG6Rty1Vk+fUOR4v9E6R6YXDFkHwhwAAAAAAAQEAAQEBagA=",
+        "cHNidP8BACoCAAAAAAFAQg8AAAAAABepFG6Rty1Vk+fUOR4v9E6R6YXDFkHwhwAAAAAAAQAAAQABagA=",
+        "cHNidP8BADMBAAAAAREREREREREREREREREREREREfrK3hERERERERERERERfwAAAAD/////AAAAAAAAAQEJ//////////8AAQEJAADK/gAAAAAAAA==",
+        "cHNidP8BADMBAAAAAREREREREREREREREREREREREfrK3hERERERERERERERfwAAAAD/////AAAAAAAAAQMErd7f7gEDBAEAAAAA",
+        "cHNidP8BADMBAAAAAREREREREREREREREREREREREfrK3hERERERERERERERfwAAAAD/////AAAAAAAAAQQAAQQBagA=",
+        "cHNidP8BADMBAAAAAREREREREREREREREREREREREfrK3hERERERERERERERfwAAAAD/////AAAAAAAAAQEJAOH1BQAAAAAAAQUAAQUBUQA=",
+        "cHNidP8BADMBAAAAAREREREREREREREREREREREREfrK3hERERERERERERERfwAAAAD/////AAAAAAAAAQcAAQcBUQA=",
+        "cHNidP8BADMBAAAAAREREREREREREREREREREREREfrK3hERERERERERERERfwAAAAD/////AAAAAAAAAQEJAOH1BQAAAAAAAQgBAAEIAwEBUQA="
     ],
     "valid" : [
         "cHNidP8BAKACAAAAAqsJSaCMWvfEm4IS9Bfi8Vqz9cM9zxU4IagTn4d6W3vkAAAAAAD+////qwlJoIxa98SbghL0F+LxWrP1wz3PFTghqBOfh3pbe+QBAAAAAP7///8CYDvqCwAAAAAZdqkUdopAu9dAy+gdmI5x3ipNXHE5ax2IrI4kAAAAAAAAGXapFG9GILVT+glechue4O/p+gOcykWXiKwAAAAAAAEHakcwRAIgR1lmF5fAGwNrJZKJSGhiGDR9iYZLcZ4ff89X0eURZYcCIFMJ6r9Wqk2Ikf/REf3xM286KdqGbX+EhtdVRs7tr5MZASEDXNxh/HupccC1AaZGoqg7ECy0OIEhfKaC3Ibi1z+ogpIAAQEgAOH1BQAAAAAXqRQ1RebjO4MsRwUPJNPuuTycA5SLx4cBBBYAFIXRNTfy4mVAWjTbr6nj3aAfuCMIAAAA",