diff --git a/agent/sidecar_service_test.go b/agent/sidecar_service_test.go
index 0cee2e374..3b4a018a5 100644
--- a/agent/sidecar_service_test.go
+++ b/agent/sidecar_service_test.go
@@ -228,7 +228,7 @@ func TestAgent_SidecarPortFromServiceID(t *testing.T) {
 		enterpriseMeta    acl.EnterpriseMeta
 		maxPort           int
 		port              int
-		preRegister       *structs.ServiceDefinition
+		preRegister       []*structs.ServiceDefinition
 		serviceID         string
 		wantPort          int
 		wantErr           string
@@ -242,34 +242,61 @@ func TestAgent_SidecarPortFromServiceID(t *testing.T) {
 			name: "re-registering same sidecar with no port should pick same one",
 			// Allow multiple ports to be sure we get the right one
 			maxPort: 2500,
-			// Pre register the sidecar we want
-			preRegister: &structs.ServiceDefinition{
-				Kind: structs.ServiceKindConnectProxy,
-				ID:   "web1-sidecar-proxy",
-				Name: "web-sidecar-proxy",
-				Port: 2222,
+			// Pre register the main service and sidecar we want
+			preRegister: []*structs.ServiceDefinition{{
+				Kind:           structs.ServiceKindConnectProxy,
+				ID:             "web1",
+				EnterpriseMeta: *structs.DefaultEnterpriseMetaInDefaultPartition(),
+				Name:           "web",
+				Port:           2221,
+				Proxy: &structs.ConnectProxyConfig{
+					DestinationServiceName: "web",
+					DestinationServiceID:   "web1",
+					LocalServiceAddress:    "127.0.0.1",
+					LocalServicePort:       1110,
+				},
+			}, {
+				Kind:           structs.ServiceKindConnectProxy,
+				ID:             "web1-sidecar-proxy",
+				EnterpriseMeta: *structs.DefaultEnterpriseMetaInDefaultPartition(),
+				Name:           "web-sidecar-proxy",
+				Port:           2222,
 				Proxy: &structs.ConnectProxyConfig{
 					DestinationServiceName: "web",
 					DestinationServiceID:   "web1",
 					LocalServiceAddress:    "127.0.0.1",
 					LocalServicePort:       1111,
 				},
-			},
-			// Register same again
-			serviceID: "web1-sidecar-proxy",
-			wantPort:  2222, // Should claim the same port as before
+			}},
+			// Register same sidecar again
+			serviceID:      "web1-sidecar-proxy",
+			enterpriseMeta: *structs.DefaultEnterpriseMetaInDefaultPartition(),
+			wantPort:       2222, // Should claim the same port as before
 		},
 		{
 			name: "all auto ports already taken",
-			// register another sidecar consuming our 1 and only allocated auto port.
-			preRegister: &structs.ServiceDefinition{
+			// register another service with sidecar consuming our 1 and only allocated auto port.
+			preRegister: []*structs.ServiceDefinition{{
+				Kind:           structs.ServiceKindConnectProxy,
+				ID:             "api1",
+				EnterpriseMeta: *structs.DefaultEnterpriseMetaInDefaultPartition(),
+				Name:           "api",
+				Port:           2221,
+				Proxy: &structs.ConnectProxyConfig{
+					DestinationServiceName: "api",
+					DestinationServiceID:   "api1",
+					LocalServiceAddress:    "127.0.0.1",
+					LocalServicePort:       1110,
+				},
+			}, {
 				Kind: structs.ServiceKindConnectProxy,
 				Name: "api-proxy-sidecar",
 				Port: 2222, // Consume the one available auto-port
 				Proxy: &structs.ConnectProxyConfig{
+					DestinationServiceID:   "api1",
 					DestinationServiceName: "api",
 				},
-			},
+			}},
 			wantErr: "none left in the configured range [2222, 2222]",
 		},
 		{
@@ -303,9 +330,11 @@ func TestAgent_SidecarPortFromServiceID(t *testing.T) {
 			a := NewTestAgent(t, hcl)
 			defer a.Shutdown()
 
-			if tt.preRegister != nil {
-				err := a.addServiceFromSource(tt.preRegister.NodeService(), nil, false, "", ConfigSourceLocal)
-				require.NoError(t, err)
+			if len(tt.preRegister) > 0 {
+				for _, s := range tt.preRegister {
+					err := a.addServiceFromSource(s.NodeService(), nil, false, "", ConfigSourceLocal)
+					require.NoError(t, err)
+				}
 			}
 
 			gotPort, err := a.sidecarPortFromServiceIDLocked(structs.ServiceID{ID: tt.serviceID, EnterpriseMeta: tt.enterpriseMeta})