A tab label is the title of the tiddler… unless the tiddler has a caption field with a value! And since multiple tiddler can have identical caption values…
How can i fix it ?
When I view the $:/core tiddler (or any other plugin tiddler) on https://TiddlyWiki.com, the tabs only show their text once (e.g., “readme” and “contents”).
Have you installed any other plugins or made any modifications to shadow tiddlers that might affect the tabs display?
I finally found the problem. I made some modifications in CodeBlockWidget to render a copy button. How can this affect the tab?