The link slug is a unique part of the URL, which describes the page’s content. For example, in this article that part of the link is simply “same-slug”.

Slugs help to increase the CTR, even though they are short. You just need to follow some essential rules. Detailed about clickable slugs: http://shortcm.xyz/slug-importance

What happens if to create the identical slugs for two links?

1) Shortening services
Shortening services forbid to create the same slugs for one domain. This is a necessary step of the shortening service work.

If you forgot which slug you added, shortening services would prevent you from making a mistake and notify about the slug existence. Change a duplicated slug to a unique one for creating an SEO-friendly URL.
Take a look at the Short.cm example.

SHORTCMM

2) Other platforms
Slug is the editable part of the URL that you can edit when writing a new post. That’s why such platforms as Wordpress, Ghost.io, Hubspot automatize the work process. These services detect the duplicated post in the database and append a “-2”, like so: test-post-2, to the post slug. Nobody likes the “dash-twos”, but they are required for the auto-creation of non-duplicate post slugs.

ghost

The reason for blocking duplicated links

Web apps block links with the same slugs. When you click on the link, you are automatically redirected to the web-page. If two identical links with different content exist, the system can't identify the right path from two ones you want to be redirected to. That is why a new rule was born: don’t create links with the duplicated slugs – this won’t lead to success.

Now check the apps you use for editing a slug of a new link. If the service lets create two links with the same slugs – contact support for a bug report.