Error with infinite urls

[zaqueon]

I have a duplicate content problem on my web. If the file ends in .php, I can add the termination you want and create a url automatically.
For example. I have this url: https://catinfog.com/tpv/tienda-ropa.php if I add at the end "/text-you-want" , it will not give 404 error.

How could you solve this error?

Thank you.