I'm trying to set up language associations, but the permalink adds the character "1" to the second post.

Should be like that:
example.com/blog/test-one/ — main link of the post
example.com/es/blog/test-one/ — link to the Spanish version of the post

But it turns out like this:
example.com/blog/test-one/ — main link of the post
example.com/es/blog/test-one-1/ — link to the Spanish version of the post