My audiobook shows the Prologue twice (for example "03. Prologue" and "04. Prologue") and the Epilogue twice after I re-rendered some chapters. How do I fix it?

Update to BookyAI version 1.9.12 or later, then on the Audio page click "Start fresh", confirm, and click "Render" once more. The duplicates came from a change in the section list after your first render: a section added or switched on before the Prologue moved every later track one number down. Earlier versions kept finished sections by their old track number, so the old Prologue and Epilogue rows stayed next to the new ones. Since 1.9.12 BookyAI recognises each section by what it is, not by its position; a moved section is re-mastered under the right number in seconds, and leftover files are removed after every render. On 1.9.12 the duplicates cannot come back.