Hi Sandeep,
You are using the JSON model, so model is already available locally.
Also I assume both model have same name , so it might be taking same value.
Some possible actions that I would consider :
1.Destroy the content of view on onExit method of both apps.
2. Giving two different model name
3. Check the console if there is some error that might have created the problem while rendering second application.
4. Check if you are setting the model in the global level ie into sap.ui.core (this should not be done while integrating into launchpad