Combined output: References to footnotes are not re-ordered

[sebix]

when using footnotes in multiple documents in combination with the combined output:

[WARNING] Duplicate note reference '1' at /tmp/mkdocs_87yitgce/document.pdf.md line 150 column 1
[WARNING] Duplicate note reference '2' at /tmp/mkdocs_87yitgce/document.pdf.md line 151 column 1
[WARNING] Duplicate note reference '1' at /tmp/mkdocs_87yitgce/document.pdf.md line 206 column 1
[WARNING] Duplicate note reference '2' at /tmp/mkdocs_87yitgce/document.pdf.md line 207 column 1
[WARNING] Duplicate note reference '3' at /tmp/mkdocs_87yitgce/document.pdf.md line 209 column 1
[WARNING] Duplicate note reference '1' at /tmp/mkdocs_87yitgce/document.pdf.md line 234 column 1
[WARNING] Duplicate note reference '2' at /tmp/mkdocs_87yitgce/document.pdf.md line 235 column 1
[WARNING] Duplicate note reference '3' at /tmp/mkdocs_87yitgce/document.pdf.md line 236 column 1
[WARNING] Duplicate note reference '1' at /tmp/mkdocs_87yitgce/document.pdf.md line 278 column 1
[WARNING] Duplicate note reference '1' at /tmp/mkdocs_87yitgce/document.pdf.md line 340 column 1
[WARNING] Duplicate note reference '2' at /tmp/mkdocs_87yitgce/document.pdf.md line 342 column 1
[WARNING] Duplicate note reference '3' at /tmp/mkdocs_87yitgce/document.pdf.md line 344 column 1
[WARNING] Duplicate note reference '4' at /tmp/mkdocs_87yitgce/document.pdf.md line 346 column 1
[WARNING] Duplicate note reference '5' at /tmp/mkdocs_87yitgce/document.pdf.md line 348 column 1
[WARNING] Duplicate note reference '1' at /tmp/mkdocs_87yitgce/document.pdf.md line 393 column 1
[WARNING] Duplicate note reference '2' at /tmp/mkdocs_87yitgce/document.pdf.md line 394 column 1
[WARNING] Duplicate note reference '3' at /tmp/mkdocs_87yitgce/document.pdf.md line 395 column 1
[WARNING] Duplicate note reference '4' at /tmp/mkdocs_87yitgce/document.pdf.md line 396 column 1
[WARNING] Duplicate note reference '5' at /tmp/mkdocs_87yitgce/document.pdf.md line 397 column 1

The reason is that all input documents are being concatenated together without any further adaptations.