Lenovo and Huawei mobile phones have 3G and G icons in the status bar and these icons indicate the mode of network of the 2 SIM cards. How to add these icons to the status bar of Samsung?
You can't add these icons to the status bar. The icons modification is based on the reception and if the data is turned on or not. Go to Settings > Wireless and networks > More Networks > Mobile Networks and change the Network modes. Switch to AUTO, then when the data is activated, you will see the icons change in the status bar based on your reception.