Thank you Abdul you were right about the single blog menu items, using the same alias solved that part of the problem.
But now I'm getting the posts getting duplicated with repeating links

https://insidepiano.com/es/lecciones-de-piano-composición-multi-tonica
https://insidepiano.com/es/lecciones-de-piano-composición-multi-tonica/lecciones-de-piano-composicion-multi-tonica

Can you please help me find this issue?

Thanks in advance!