diff --git a/CHANGELOG.md b/CHANGELOG.md
index 904c160f5b61..f5def7b3c51a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -44,6 +44,7 @@ __BACKWARDS INCOMPATIBILITIES:__
 BUG FIXES:
 
  * agent (Enterprise): Fixed a bug where audit logging caused websocket and streaming http endpoints to fail [[GH-9319](https://github.com/hashicorp/nomad/issues/9319)]
+ * api: Fixed a bug where AllocatedResources contained increasingly duplicated ports [[GH-9368](https://github.com/hashicorp/nomad/issues/9368)]
  * core: Fixed a bug where ACL handling prevented cross-namespace allocation listing [[GH-9278](https://github.com/hashicorp/nomad/issues/9278)]
  * core: Fixed a bug where scaling policy filtering would ignore type query if job query was present [[GH-9312](https://github.com/hashicorp/nomad/issues/9312)]
  * core: Fixed a bug where a request to scale a job would fail if the job was not in the default namespace. [[GH-9296](https://github.com/hashicorp/nomad/pull/9296)]
diff --git a/command/agent/alloc_endpoint.go b/command/agent/alloc_endpoint.go
index 5b7b8ee086c7..20865144864a 100644
--- a/command/agent/alloc_endpoint.go
+++ b/command/agent/alloc_endpoint.go
@@ -127,6 +127,7 @@ func (s *HTTPServer) allocGet(allocID string, resp http.ResponseWriter, req *htt
 	alloc.SetEventDisplayMessages()
 
 	// Handle 0.12 ports upgrade path
+	alloc = alloc.Copy()
 	alloc.AllocatedResources.Canonicalize()
 
 	return alloc, nil
diff --git a/command/agent/alloc_endpoint_test.go b/command/agent/alloc_endpoint_test.go
index 6d36d2658e6b..cf94c791dfe2 100644
--- a/command/agent/alloc_endpoint_test.go
+++ b/command/agent/alloc_endpoint_test.go
@@ -158,47 +158,42 @@ func TestHTTP_AllocsPrefixList(t *testing.T) {
 
 func TestHTTP_AllocQuery(t *testing.T) {
 	t.Parallel()
+	require := require.New(t)
 	httpTest(t, nil, func(s *TestAgent) {
 		// Directly manipulate the state
 		state := s.Agent.server.State()
 		alloc := mock.Alloc()
-		if err := state.UpsertJobSummary(999, mock.JobSummary(alloc.JobID)); err != nil {
-			t.Fatal(err)
-		}
-		err := state.UpsertAllocs(structs.MsgTypeTestSetup, 1000, []*structs.Allocation{alloc})
-		if err != nil {
-			t.Fatalf("err: %v", err)
-		}
+		require.NoError(state.UpsertJobSummary(999, mock.JobSummary(alloc.JobID)))
+		require.NoError(state.UpsertAllocs(structs.MsgTypeTestSetup, 1000, []*structs.Allocation{alloc}))
 
 		// Make the HTTP request
 		req, err := http.NewRequest("GET", "/v1/allocation/"+alloc.ID, nil)
-		if err != nil {
-			t.Fatalf("err: %v", err)
-		}
+		require.NoError(err)
 		respW := httptest.NewRecorder()
 
 		// Make the request
 		obj, err := s.Server.AllocSpecificRequest(respW, req)
-		if err != nil {
-			t.Fatalf("err: %v", err)
-		}
+		require.NoError(err)
 
 		// Check for the index
-		if respW.HeaderMap.Get("X-Nomad-Index") == "" {
-			t.Fatalf("missing index")
-		}
-		if respW.HeaderMap.Get("X-Nomad-KnownLeader") != "true" {
-			t.Fatalf("missing known leader")
-		}
-		if respW.HeaderMap.Get("X-Nomad-LastContact") == "" {
-			t.Fatalf("missing last contact")
-		}
+		require.NotEmpty(respW.Header().Get("X-Nomad-Index"), "missing index")
+		require.Equal("true", respW.Header().Get("X-Nomad-KnownLeader"), "missing known leader")
+		require.NotEmpty(respW.Header().Get("X-Nomad-LastContact"), "missing last contact")
 
 		// Check the job
 		a := obj.(*structs.Allocation)
-		if a.ID != alloc.ID {
-			t.Fatalf("bad: %#v", a)
-		}
+		require.Equal(a.ID, alloc.ID)
+
+		// Check the number of ports
+		require.Len(a.AllocatedResources.Shared.Ports, 2)
+
+		// Make the request again
+		respW = httptest.NewRecorder()
+		obj, err = s.Server.AllocSpecificRequest(respW, req)
+		require.NoError(err)
+		a = obj.(*structs.Allocation)
+		// Check the number of ports again
+		require.Len(a.AllocatedResources.Shared.Ports, 2)
 	})
 }