There is already one extension is installed and published in Production environment.
I have updated code(done more development) in the same package, it is successfully compiled and package created(.app file) in extension folder in sandbox environment.
Now issue is what when I am going to upload that package into production environment, it is getting failed with below error message.
"Deploy Operation rejected. Error: An extension with same App ID and version has already been uploaded. Resolve and deploy again.;"
I tried to change Version in app.json file but it didn't work.
Thanks RedFoxUA and Erik for reply.
I have successfully deploy extension package.
What I have done, I have update version change schemaupdate to recreate and publish on sandbox. Again, I have change schemaUpdateMode to "schemaUpdateMode": "Synchronize" and publish on sandbox.
Now I have upload latest .app file in production environment and it is successfully uploaded.
P.S : I have not unpublished and uninstall version 126.96.36.199.
So, there is two extension package with same name but different version.