Hey @Test 

Welcome to the Community.

The most preferred approach here will be to send data from each of your applications into different projects under your org account.

Ideally you would want to send data for each of your multiple applications into separate projects and analyze individually if each application behaves differently wrt users and platforms.

If you expect users to crossover between platforms/applications, then you can leverage the cross project view to analyze their behavior across your product portfolio, You can read more on that here.

Let me know if I have interpreted your use case correctly. Hope this helps.

So both applications are managed by different teams within the same organization and both apps are different in nature. Is creating a different project under the same organization is preferred over creating a different organization on Amplitude?

Yup. The ideal way to manage this setup is to create separate projects for each app under the same organization. If you are just starting out, one of the best practices is to have two separate projects for each app - one for testing data and another for production data. Here is a quick start guide which can help you move forward.

Why Amplitude set same ID to a user that is totally new to a fresh project? Can we avoid this or is it okay to have this kind of scenario? Use case: We have 2 different projects for two different apps, when same device is used to create account for fresh app amplitude remember the User ID from previous project of a different app.