Samsung Galaxy Grand 2 DUOS (SM-G7102) users who wish to root their devices, may follow our step-by-step guide.
This tutorial uses Pre-Rooted Stock Firmware released by Senior Member of XDA-Developers, balliboxer.
Firmware details
PDA: G7102XXUANA5
Version: Android 4.3
Build date: Feb 16, 2014
Features
- Full Stock Based- PreRooted- Blotwares r 

Disclaimer: We and the developer of this rooting procedures shall not be held responsible if any undesirable outcomes may happen to your device. use of this root guide is solely at your own risk!
Pre-requisites
1. Install USB Drivers for Samsung Galaxy Grand 2 on the computer.
2. Enable USB Debugging Mode on the phone by navigating to Settings >> Developer Options.
3. Make a backup of all your important data before following the guide.
4. The Galaxy Grand 2 should be factory unlocked and not locked to any particular carrier.
5. Ensure the battery of the phone is charged more than 80 percent.
6. The Pre-Rooted Firmware works only on the Galaxy Grand 2 with dual SIM card slots also known as Galaxy Grand 2 DUOS (SM-G7102). Applying this to any incorrect variant might brick the device. Verify the model number of the Galaxy Grand 2 by navigating to Settings >> About Phone.

Files Required
1. Android 4.3 XXUANA5 Jelly Bean Pre-Rooted Firmware for Galaxy Grand 2 DUOS SM-G7102
2. Odin 3.09

Steps to Root Galaxy Grand 2 DUOS SM-G7102 with Pre-Rooted Firmware
Step 1: Extract Pre-Rooted Firmware and Odin 3.09 files using WinRAR/7-Zip/WinZip or any other extracting tool.
Step 2: Switch off the Galaxy Grand 2. Then boot into Download Mode by pressing and holding Volume Down, Home and Power buttons together until a construction Android robot icon with a warning triangle appears on screen. Now press the Volume Up button to enter Download Mode.
Step 3: Launch Odin on the computer as an Administrator.
Step 4: Connect the Galaxy Grand 2 to the computer using USB cable while it is in the Download Mode. Wait until Odin detects the device. When the device is connected successfully, the ID: COM box will turn to light blue with the COM port number. Additionally, the successful connected will be indicated by a message saying Added.

Note: If the Added message does not appear, then try re-install USB drivers or changing the port on the computer.

Step 5: In Odin, click the AP button and select the Pre-Rooted Firmware .tar.md5 file.
Step 6: Verify that Auto Reboot and F. Reset Time checkboxes are selected in Odin. Also, ensure the Re-Partition option is NOT selected.
Step 7: Double-check and click Start in Odin. The installation process will now begin.
Step 8: Once the installation process completes, your phone will restart and soon you will see a PASS message with green background in the left-most box at the very top of the Odin. You can now unplug the USB cable to disconnect it from the computer.
Related Article :How to Root Samsung Galaxy Grand 2 DUOS SM-G7102 with Android 4.3 XXUANA2 Jelly Bean Pre-Rooted Firmware Using Odin Guide
Samsung Galaxy Grand 2 DUOS SM-G7102 is now rooted successfully. Open the app drawer of the phone and check for an app called SuperSU. Verify the root status of the device by downloading Root Checker app from Google Play Store.

Note: If the device is stuck in boot loop after Step 8, then go to recovery mode (press and hold the Volume Up, Home and Power buttons together) and choose Wipe Data/Factory Reset and Wipe Cache Partition. Finally, return to main recovery menu and select Reboot System Now. Please note that performing wiping task will erase your device internal memory data and not external SD card data.

Screenshot: Rooted successfully!

Thanks to all fellas at XDA who first tried out this rooting technique. This method was originally posted via XDA-Developers original thread.