Problem with URL of translated page

Hello. I have a website with URL like example.com/my-page/. I have chosen the URL of translated pages to look like example.com/en/my-page/.
BUT
In fact the URL of a translated page looks like example.com/en/my-page-2/.
Do you know how to fix it so I can have example.com/my-page/ and example.com/en/my-page/? Thanks