FCM notification open my app again when it's in background

[Muhannd Dhahier]

My App has 2 activates

1- SplashScreen : code in  the manifest file

<activity
    android:name=".SplashScreen"
    android:configChanges="orientation|keyboardHidden"
    android:screenOrientation="portrait"
    android:theme="@style/AppTheme.NoActionBar"
    android:launchMode="singleTop">
    <intent-filter>
        <action android:name="android.intent.action.MAIN" />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>

2- MainActivity:  code in  the manifest file

<activity android:name=".MainActivity"
    android:configChanges="orientation|keyboardHidden"
    android:screenOrientation="portrait"

   >
    <intent-filter>
        <action
            android:name="android.intent.action.default"
           />
        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

and I have a class MyFireMsgServic that build my notification

Intent intent = new Intent(this, MainActivity.class);
    intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
    PendingIntent contentIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_CANCEL_CURRENT);

    NotificationCompat.Builder b = new NotificationCompat.Builder(this);



    b.setAutoCancel(true)
            .setDefaults(Notification.DEFAULT_ALL)
            .setWhen(System.currentTimeMillis())
            .setSmallIcon(R.drawable.trans_icon)
            .setContentTitle(title)
            .setContentText(message)
            .setSound(sound)
            .setDefaults(Notification.DEFAULT_LIGHTS)
            .setContentIntent(contentIntent);



    NotificationManager notificationManager = (NotificationManager) this.getSystemService(Context.NOTIFICATION_SERVICE);
    notificationManager.notify(1, b.build());
}

I used FCM to send notification to my app, the issue is when my App in background and click on  the notification it start an another instance of my app