Well, thank you very much for replying, Tommy. But the solution seems a bit too onerous.
Your Question: Did the Duplicate chrome window is same or the tab page has been split into several?
Reply: It is the same window that is duplicated.
BTW, there are other people too who are facing the same problem. You should probably take a look at the given link to know what the problem exactly is: https://answers.microsoft.com/en-us/windows/forum/all/multiple-chrome-instances-showing-up-in-alt-tab/fa6f5b71-ef4b-4814-a2f1-ddf17d47b824?page=1