Hello,
iCagenda never add an article when you add an event !!!
If you have this behavior, this is NOT processed by iCagenda, but by a third party extension (plugin) you have installed, which is overriding iCagenda behavior (and maybe other extensions...).
...
If you check iCagenda code, you will found nothing link to the content database table. TO search which extension that does such automatic addition of articles, and you don't know which one, check code for an not related Joomla extension, which has something like this "__content" (2 underscores with content means SQL request to com_content (articles))
Hope this helps ?
Regards,
Cyril