I using v1.8.18 and suddenly experiencing a new issue. At first my wife noticed it but I chalked it up to her possibly double tapping the publish button, but I have had other site now do the same.
If you select multiple categories, the plugin will post to facebook once for each category selected to both personal pages and fan pages. Really odd. Granted, I haven't tried more than 2 categories since this started happening but I have confirmed it on 4 different sites using the plugin.