`import` ignored, when importing second XSD into the same namespace

I have this document and an XSD (linked from it from schemaLocation).

Now, the XSD imports 2 other XSDs with the same targetNamespace:

  <xs:import namespace="http://dia.gov.cz/ns/spolecne-casti-elektronickych-dokumentu/osoby" schemaLocation="https://ofn.gov.cz/společné-části-elektronických-dokumentů/2024-10-04/schémata/osoby/osoba-ve-vztahu-k-dokumentu.xsd"/>
  <xs:import namespace="http://dia.gov.cz/ns/spolecne-casti-elektronickych-dokumentu/osoby" schemaLocation="https://ofn.gov.cz/společné-části-elektronických-dokumentů/2024-10-04/schémata/osoby/fyzická-osoba-ve-vztahu-k-dokumentu.xsd"/>

The XSDs have both the same targetNamespace and contain no conflicting definitions. Nevertheless, the second import is ignored, resulting in an error:

because that type is defined in the second imported XSD. When I comment out the first import, the second starts working.

This should be legal in XML Schema, and other validators like Altova work fine with it.

Reproduce the problem with document1.xml and dokument-z-formuláře-ZoPDS.xsd, following its two imports of osoba-ve-vztahu-k-dokumentu.xsd and fyzická-osoba-ve-vztahu-k-dokumentu.xsd. Trace the XML Schema import and validation entry point; done means both same-namespace schemas are processed and the type from the second schema resolves without the reported error.