diff --git a/tests/unit-tests/security/pib/detail/identity-impl.t.cpp b/tests/unit-tests/security/pib/detail/identity-impl.t.cpp
index 10c7bb8..2f35d2f 100644
--- a/tests/unit-tests/security/pib/detail/identity-impl.t.cpp
+++ b/tests/unit-tests/security/pib/detail/identity-impl.t.cpp
@@ -121,6 +121,18 @@
   BOOST_CHECK_THROW(identity1.getDefaultKey(), Pib::Error);
 }
 
+BOOST_AUTO_TEST_CASE(Overwrite)
+{
+  auto pibImpl = make_shared<pib::PibMemory>();
+  IdentityImpl identity1(id1, pibImpl, true);
+
+  identity1.addKey(id1Key1.buf(), id1Key1.size(), id1Key1Name);
+  BOOST_CHECK(identity1.getKey(id1Key1Name).getPublicKey() == id1Key1);
+
+  identity1.addKey(id1Key2.buf(), id1Key2.size(), id1Key1Name); // overwriting key should work
+  BOOST_CHECK(identity1.getKey(id1Key1Name).getPublicKey() == id1Key2);
+}
+
 BOOST_AUTO_TEST_CASE(Errors)
 {
   auto pibImpl = make_shared<pib::PibMemory>();
@@ -129,7 +141,6 @@
   IdentityImpl identity1(id1, pibImpl, true);
 
   identity1.addKey(id1Key1.buf(), id1Key1.size(), id1Key1Name);
-  BOOST_CHECK_THROW(identity1.addKey(id1Key1.buf(), id1Key1.size(), id1Key1Name), Pib::Error);
   BOOST_CHECK_THROW(identity1.addKey(id2Key1.buf(), id2Key1.size(), id2Key1Name), std::invalid_argument);
   BOOST_CHECK_THROW(identity1.removeKey(id2Key1Name), std::invalid_argument);
   BOOST_CHECK_THROW(identity1.getKey(id2Key1Name), std::invalid_argument);
diff --git a/tests/unit-tests/security/pib/detail/key-impl.t.cpp b/tests/unit-tests/security/pib/detail/key-impl.t.cpp
index b25a870..5257113 100644
--- a/tests/unit-tests/security/pib/detail/key-impl.t.cpp
+++ b/tests/unit-tests/security/pib/detail/key-impl.t.cpp
@@ -25,6 +25,7 @@
 #include "../pib-data-fixture.hpp"
 
 #include "boost-test.hpp"
+#include "identity-management-fixture.hpp"
 
 namespace ndn {
 namespace security {
@@ -130,13 +131,49 @@
   BOOST_CHECK_EQUAL(key11.getCertificates().size(), 0);
 }
 
+class OverwriteFixture : public ndn::security::tests::PibDataFixture,
+                         public ndn::tests::IdentityManagementFixture
+{
+};
+
+BOOST_FIXTURE_TEST_CASE(Overwrite, OverwriteFixture)
+{
+  auto pibImpl = make_shared<pib::PibMemory>();
+
+  BOOST_CHECK_THROW(KeyImpl(id1Key1Name, pibImpl), Pib::Error);
+  KeyImpl(id1Key1Name, id1Key1.buf(), id1Key1.size(), pibImpl);
+  KeyImpl key1(id1Key1Name, pibImpl);
+
+  KeyImpl(id1Key1Name, id1Key2.buf(), id1Key2.size(), pibImpl); // overwriting of the key should work
+  KeyImpl key2(id1Key1Name, pibImpl);
+
+  BOOST_CHECK(key1.getPublicKey() != key2.getPublicKey()); // key1 cached the original public key
+  BOOST_CHECK(key2.getPublicKey() == id1Key2);
+
+  key1.addCertificate(id1Key1Cert1);
+  BOOST_CHECK_EQUAL(key1.getCertificate(id1Key1Cert1.getName()), id1Key1Cert1);
+
+  auto otherCert = id1Key1Cert1;
+  SignatureInfo info;
+  info.setValidityPeriod(ValidityPeriod(time::system_clock::now(),
+                                        time::system_clock::now() + time::seconds(1)));
+  m_keyChain.sign(otherCert, SigningInfo().setSignatureInfo(info));
+
+  BOOST_CHECK_EQUAL(otherCert.getName(), id1Key1Cert1.getName());
+  BOOST_CHECK(otherCert.getContent() == id1Key1Cert1.getContent());
+  BOOST_CHECK_NE(otherCert, id1Key1Cert1);
+
+  key1.addCertificate(otherCert);
+
+  BOOST_CHECK_EQUAL(key1.getCertificate(id1Key1Cert1.getName()), otherCert);
+}
+
 BOOST_AUTO_TEST_CASE(Errors)
 {
   auto pibImpl = make_shared<pib::PibMemory>();
 
   BOOST_CHECK_THROW(KeyImpl(id1Key1Name, pibImpl), Pib::Error);
   KeyImpl key11(id1Key1Name, id1Key1.buf(), id1Key1.size(), pibImpl);
-  BOOST_CHECK_THROW(KeyImpl(id1Key1Name, id1Key1.buf(), id1Key1.size(), pibImpl), Pib::Error);
 
   BOOST_CHECK_THROW(KeyImpl(Name("/wrong"), pibImpl), std::invalid_argument);
   BOOST_CHECK_THROW(KeyImpl(Name("/wrong"), id1Key1.buf(), id1Key1.size(), pibImpl), std::invalid_argument);
@@ -144,7 +181,6 @@
   BOOST_CHECK_THROW(KeyImpl(id1Key2Name, wrongKey.buf(), wrongKey.size(), pibImpl), std::invalid_argument);
 
   key11.addCertificate(id1Key1Cert1);
-  BOOST_CHECK_THROW(key11.addCertificate(id1Key1Cert1), Pib::Error);
   BOOST_CHECK_THROW(key11.addCertificate(id1Key2Cert1), std::invalid_argument);
   BOOST_CHECK_THROW(key11.removeCertificate(id1Key2Cert1.getName()), std::invalid_argument);
   BOOST_CHECK_THROW(key11.getCertificate(id1Key2Cert1.getName()), std::invalid_argument);
diff --git a/tests/unit-tests/security/v2/key-chain.t.cpp b/tests/unit-tests/security/v2/key-chain.t.cpp
index 950b97e..4eaf75e 100644
--- a/tests/unit-tests/security/v2/key-chain.t.cpp
+++ b/tests/unit-tests/security/v2/key-chain.t.cpp
@@ -228,8 +228,7 @@
   m_keyChain.addCertificate(key3, key3Cert1);
   BOOST_CHECK_EQUAL(key3.getCertificates().size(), 1);
   BOOST_REQUIRE_NO_THROW(key3.getDefaultCertificate());
-  // Overwrite the same cert again, should throw Pib::Error.
-  BOOST_REQUIRE_THROW(m_keyChain.addCertificate(key3, key3Cert1), Pib::Error);
+  m_keyChain.addCertificate(key3, key3Cert1); // overwriting the cert should work
   BOOST_CHECK_EQUAL(key3.getCertificates().size(), 1);
   // Add another cert
   Certificate key3Cert2 = key3Cert1;