It looks like two things are going on here:
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You (or someone) has configured the Argomenti Figli relation view to show entities from two related databases (Argomenti Figli AND Riferimenti Libri).
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The smart folder is configured to show Argomenti Figli as the top level (with recursion enabled) and Riferimenti a Siti and Riferimenti Libri as levels below.
These configurations are independent of each other.