diff --git a/server/client.go b/server/client.go
index 5a115f72..2af3928f 100644
--- a/server/client.go
+++ b/server/client.go
@@ -2165,7 +2165,8 @@ func (c *client) processSub(argo []byte, noForward bool) (*subscription, error)
 	var err error
 
 	// Subscribe here.
-	if c.subs[sid] == nil {
+	es := c.subs[sid]
+	if es == nil {
 		c.subs[sid] = sub
 		if acc != nil && acc.sl != nil {
 			err = acc.sl.Insert(sub)
@@ -2186,6 +2187,11 @@ func (c *client) processSub(argo []byte, noForward bool) (*subscription, error)
 		c.sendOK()
 	}
 
+	// If it was already registered, return it.
+	if es != nil {
+		return es, nil
+	}
+
 	// No account just return.
 	if acc == nil {
 		return sub, nil
diff --git a/test/new_routes_test.go b/test/new_routes_test.go
index fbd1002b..8356eff5 100644
--- a/test/new_routes_test.go
+++ b/test/new_routes_test.go
@@ -1118,6 +1118,11 @@ func addServiceExport(subject string, authorized []*server.Account, targets ...*
 var isPublic = []*server.Account(nil)
 
 func TestNewRouteStreamImport(t *testing.T) {
+	testNewRouteStreamImport(t, false)
+}
+
+func testNewRouteStreamImport(t *testing.T, duplicateSub bool) {
+	t.Helper()
 	srvA, srvB, optsA, optsB := runServers(t)
 	defer srvA.Shutdown()
 	defer srvB.Shutdown()
@@ -1143,7 +1148,11 @@ func TestNewRouteStreamImport(t *testing.T) {
 	defer clientB.Close()
 
 	sendB, expectB := setupConnWithAccount(t, clientB, "$bar")
-	sendB("SUB foo 1\r\nPING\r\n")
+	sendB("SUB foo 1\r\n")
+	if duplicateSub {
+		sendB("SUB foo 1\r\n")
+	}
+	sendB("PING\r\n")
 	expectB(pongRe)
 
 	// The subscription on "foo" for account $bar will also become
@@ -1833,3 +1842,52 @@ func TestNewRouteLeafNodeOriginSupport(t *testing.T) {
 		t.Fatalf("Should not have received the message on bar")
 	}
 }
+
+// Check that real duplicate subscription (that is, sent by client with same sid)
+// are ignored and do not register multiple shadow subscriptions.
+func TestNewRouteDuplicateSubscription(t *testing.T) {
+	// This is same test than TestNewRouteStreamImport but calling "SUB foo 1" twice.
+	testNewRouteStreamImport(t, true)
+
+	opts := LoadConfig("./configs/new_cluster.conf")
+	opts.DisableShortFirstPing = true
+	s := RunServer(opts)
+	defer s.Shutdown()
+
+	rc := createRouteConn(t, opts.Cluster.Host, opts.Cluster.Port)
+	defer rc.Close()
+
+	routeID := "RTEST_DUPLICATE:22"
+	routeSend, routeExpect := setupRouteEx(t, rc, opts, routeID)
+	info := checkInfoMsg(t, rc)
+	info.ID = routeID
+	b, err := json.Marshal(info)
+	if err != nil {
+		t.Fatalf("Could not marshal test route info: %v", err)
+	}
+	routeSend(fmt.Sprintf("INFO %s\r\n", b))
+	routeSend("PING\r\n")
+	routeExpect(pongRe)
+
+	c := createClientConn(t, opts.Host, opts.Port)
+	defer c.Close()
+	send, expect := setupConn(t, c)
+
+	// Create a real duplicate subscriptions (same sid)
+	send("SUB foo 1\r\nSUB foo 1\r\nPING\r\n")
+	expect(pongRe)
+
+	// Route should receive single RS+
+	routeExpect(rsubRe)
+
+	// Unsubscribe.
+	send("UNSUB 1\r\nPING\r\n")
+	expect(pongRe)
+
+	// Route should receive RS-.
+	// With defect, only 1 subscription would be found during the unsubscribe,
+	// however route map would have been updated twice when processing the
+	// duplicate SUB, which means that the RS- would not be received because
+	// the count would still be 1.
+	routeExpect(runsubRe)
+}