Hi anjuanju810,
Thanks for using Apple Support Communities. We understand you have some questions about setting AirPods up with a different case. You may be able to accomplish this if they are the same model using the steps here:
1. On your iPhone, iPad, or iPod touch, go to Settings > Bluetooth and tap the Information button
next to your AirPods.
2. Tap Forget This Device.
3. Tap Forget Device, and tap again to confirm.
4. Put both AirPods in your charging case.
5. Open the lid and check the status light. It should flash amber.
6. Press and hold the setup button on the back of the case for a few seconds. The status light should flash white.*
7. Go to the Home Screen on your iPhone, iPad, or iPod touch.
8. Open the case—with your AirPods inside—and hold it next to your iPhone, iPad, or iPod touch. A setup animation appears on your screen.
9. Tap Connect, then tap Done.
See more here: Set up your replacement AirPods or charging case - Apple Support
Thanks.