Hello Surabhi,
As per my understanding and based on the discussion with Adobe Product Team we should avoid such kinds of configurations.
According to documentation [0], Alias is just a different name for a resource under a path.
If you have following resources:
/content/x/y/z/test
and you create another resource with an alias name (alias name same as the resource in the previous step) under same path:
/content/x/y/z/test_new - sling:alias="test"
You would end up in creating two resources with same path ("/content/x/y/z/test") which may lead to unexpected results.
Also, The second issue that you have highlighted that Whenever we are activating the Alias Page then at that time Original page is also getting activated.
I believe this use-case is incorrect as you are keeping two resources under same path - which should not be allowed on Author instance as I have explained above.
[0] https://sling.apache.org/documentation/the-sling-engine/mappings-for-resource-resolution.html#alias-...