Hello, @toriellomr
Thank you for contacting us regarding your question!
Let you explain the reason why you see such a result.
You are using a fixed Header in the table.
When you use it, a separate table is created under this header.
The main table exists as it was. It displays data and header as well. This is a feature of the table engine.
But in fact you see one table on the Front-End.
I draw your attention to the fact that duplication is generated only on the Front-End. The server receives data without duplication.