Install Two same apk but using different WebService Url

Question

My Client is looking for two different android application on their phone one for testing purpose and one for the production. Testing application will be used by the client to show the demo's to different third level clients. I am using "com.xyz" as a application id for my android application I want to build two different apk's but with the same application id this is because I have a project created on google console with say "com.xyz" for push notification. If I change the application id for another application then push notification won't be able to work. I have seen the process of using build variant for different flavors but have not tried yet. In lots of examples in different flavors I have seen that the application id's are different for the different flavor. If application id is different then will my application be able to get push notifications.