diff --git a/src/policy/packages.cpp b/src/policy/packages.cpp
index 6e70a94088a..a901ef8f38c 100644
--- a/src/policy/packages.cpp
+++ b/src/policy/packages.cpp
@@ -37,6 +37,13 @@ bool CheckPackage(const Package& txns, PackageValidationState& state)
     std::unordered_set<uint256, SaltedTxidHasher> later_txids;
     std::transform(txns.cbegin(), txns.cend(), std::inserter(later_txids, later_txids.end()),
                    [](const auto& tx) { return tx->GetHash(); });
+
+    // Package must not contain any duplicate transactions, which is checked by txid. This also
+    // includes transactions with duplicate wtxids and same-txid-different-witness transactions.
+    if (later_txids.size() != txns.size()) {
+        return state.Invalid(PackageValidationResult::PCKG_POLICY, "package-contains-duplicates");
+    }
+
     for (const auto& tx : txns) {
         for (const auto& input : tx->vin) {
             if (later_txids.find(input.prevout.hash) != later_txids.end()) {
diff --git a/src/test/txpackage_tests.cpp b/src/test/txpackage_tests.cpp
index c08d2748a62..01f0a836a3f 100644
--- a/src/test/txpackage_tests.cpp
+++ b/src/test/txpackage_tests.cpp
@@ -66,6 +66,17 @@ BOOST_FIXTURE_TEST_CASE(package_sanitization_tests, TestChain100Setup)
     BOOST_CHECK(!CheckPackage(package_too_large, state_too_large));
     BOOST_CHECK_EQUAL(state_too_large.GetResult(), PackageValidationResult::PCKG_POLICY);
     BOOST_CHECK_EQUAL(state_too_large.GetRejectReason(), "package-too-large");
+
+    // Packages can't contain transactions with the same txid.
+    Package package_duplicate_txids_empty;
+    for (auto i{0}; i < 3; ++i) {
+        CMutableTransaction empty_tx;
+        package_duplicate_txids_empty.emplace_back(MakeTransactionRef(empty_tx));
+    }
+    PackageValidationState state_duplicates;
+    BOOST_CHECK(!CheckPackage(package_duplicate_txids_empty, state_duplicates));
+    BOOST_CHECK_EQUAL(state_duplicates.GetResult(), PackageValidationResult::PCKG_POLICY);
+    BOOST_CHECK_EQUAL(state_duplicates.GetRejectReason(), "package-contains-duplicates");
 }
 
 BOOST_FIXTURE_TEST_CASE(package_validation_tests, TestChain100Setup)
diff --git a/test/functional/rpc_packages.py b/test/functional/rpc_packages.py
index ae1a498e28a..9c4960aa1ea 100755
--- a/test/functional/rpc_packages.py
+++ b/test/functional/rpc_packages.py
@@ -212,8 +212,8 @@ class RPCPackagesTest(BitcoinTestFramework):
         coin = self.wallet.get_utxo()
 
         # tx1 and tx2 share the same inputs
-        tx1 = self.wallet.create_self_transfer(utxo_to_spend=coin)
-        tx2 = self.wallet.create_self_transfer(utxo_to_spend=coin)
+        tx1 = self.wallet.create_self_transfer(utxo_to_spend=coin, fee_rate=DEFAULT_FEE)
+        tx2 = self.wallet.create_self_transfer(utxo_to_spend=coin, fee_rate=2*DEFAULT_FEE)
 
         # Ensure tx1 and tx2 are valid by themselves
         assert node.testmempoolaccept([tx1["hex"]])[0]["allowed"]
@@ -222,8 +222,8 @@ class RPCPackagesTest(BitcoinTestFramework):
         self.log.info("Test duplicate transactions in the same package")
         testres = node.testmempoolaccept([tx1["hex"], tx1["hex"]])
         assert_equal(testres, [
-            {"txid": tx1["txid"], "wtxid": tx1["wtxid"], "package-error": "conflict-in-package"},
-            {"txid": tx1["txid"], "wtxid": tx1["wtxid"], "package-error": "conflict-in-package"}
+            {"txid": tx1["txid"], "wtxid": tx1["wtxid"], "package-error": "package-contains-duplicates"},
+            {"txid": tx1["txid"], "wtxid": tx1["wtxid"], "package-error": "package-contains-duplicates"}
         ])
 
         self.log.info("Test conflicting transactions in the same package")