As you might be aware that your Grand 2 supports dual SIM, here are some easy steps to manage them.
Go to Settings -> Device and tap on SIM card manager. On the SIM card manager screen you could see there are two SIM card slots.
Tap on SIM1, it opens up the screen where you can change the icons of the SIM and also the name you wish to.
Tap on Select icon, where it shows up list of icons you could choose from. Also when you tap on Register name you could change the default SIM card name as Aircel or Airtel as per the Service Provider or what ever name you wish to.
Use the Data service network to set the SIM card that has 3G enabled. When this is set and when you try to access your 3G the mobile data is accessed. There is also an option where you can receive incoming call via other SIM card while you use the data service. This options is under the heading General.
In Samsung Galaxy Grand 2, Smart dual SIM allows you to receive calls from both SIM card i.e. while on call on SIM1, you still get call from SIM2 and it will show as call waiting.