diff --git a/libp2p/peer/peerdata.py b/libp2p/peer/peerdata.py
index 017def66..b6d04495 100644
--- a/libp2p/peer/peerdata.py
+++ b/libp2p/peer/peerdata.py
@@ -55,7 +55,9 @@ class PeerData(IPeerData):
         """
         :param addrs: multiaddresses to add
         """
-        self.addrs.extend(addrs)
+        for addr in addrs:
+            if addr not in self.addrs:
+                self.addrs.append(addr)
 
     def get_addrs(self) -> List[Multiaddr]:
         """
diff --git a/tests/core/peer/test_peerdata.py b/tests/core/peer/test_peerdata.py
new file mode 100644
index 00000000..0f7f5651
--- /dev/null
+++ b/tests/core/peer/test_peerdata.py
@@ -0,0 +1,94 @@
+import unittest
+from unittest.mock import (
+    MagicMock,
+)
+
+from multiaddr import (
+    Multiaddr,
+)
+
+from libp2p.crypto.keys import (
+    PrivateKey,
+    PublicKey,
+)
+from libp2p.peer.peerdata import (
+    PeerData,
+    PeerDataError,
+)
+
+
+class TestPeerData(unittest.TestCase):
+    def setUp(self):
+        # This will run before each test method
+        self.peer_data = PeerData()
+        self.mock_pubkey = MagicMock(PublicKey)
+        self.mock_privkey = MagicMock(PrivateKey)
+        self.mock_addr = MagicMock(Multiaddr)
+
+    def test_get_protocols_empty(self):
+        # Test case when no protocols have been added
+        self.assertEqual(self.peer_data.get_protocols(), [])
+
+    def test_add_protocols(self):
+        # Test case when adding protocols
+        protocols = ["protocol1", "protocol2"]
+        self.peer_data.add_protocols(protocols)
+        self.assertEqual(self.peer_data.get_protocols(), protocols)
+
+    def test_set_protocols(self):
+        # Test case when setting protocols
+        protocols = ["protocolA", "protocolB"]
+        self.peer_data.set_protocols(protocols)
+        self.assertEqual(self.peer_data.get_protocols(), protocols)
+
+    def test_add_addrs(self):
+        # Test case when adding addresses
+        addresses = [self.mock_addr]
+        self.peer_data.add_addrs(addresses)
+        self.assertEqual(self.peer_data.get_addrs(), addresses)
+
+    def test_add_dup_addrs(self):
+        # Test case when adding same address more than once
+        addresses = [self.mock_addr, self.mock_addr]
+        self.peer_data.add_addrs(addresses)
+        self.peer_data.add_addrs(addresses)
+        self.assertEqual(self.peer_data.get_addrs(), [self.mock_addr])
+
+    def test_clear_addrs(self):
+        # Test case for clearing addresses
+        addresses = [self.mock_addr]
+        self.peer_data.add_addrs(addresses)
+        self.peer_data.clear_addrs()
+        self.assertEqual(self.peer_data.get_addrs(), [])
+
+    def test_put_metadata(self):
+        # Test case for adding metadata
+        key = "key1"
+        value = "value1"
+        self.peer_data.put_metadata(key, value)
+        self.assertEqual(self.peer_data.get_metadata(key), value)
+
+    def test_get_metadata_key_not_found(self):
+        # Test case for key not found in metadata
+        with self.assertRaises(PeerDataError):
+            self.peer_data.get_metadata("nonexistent_key")
+
+    def test_add_pubkey(self):
+        # Test case for adding public key
+        self.peer_data.add_pubkey(self.mock_pubkey)
+        self.assertEqual(self.peer_data.get_pubkey(), self.mock_pubkey)
+
+    def test_get_pubkey_not_found(self):
+        # Test case when public key is not set
+        with self.assertRaises(PeerDataError):
+            self.peer_data.get_pubkey()
+
+    def test_add_privkey(self):
+        # Test case for adding private key
+        self.peer_data.add_privkey(self.mock_privkey)
+        self.assertEqual(self.peer_data.get_privkey(), self.mock_privkey)
+
+    def test_get_privkey_not_found(self):
+        # Test case when private key is not set
+        with self.assertRaises(PeerDataError):
+            self.peer_data.get_privkey()