Automatically posts older articles to our facebook site

Hello!

We have a big problem with this plugin or maybe wordpress.

We use this plugin to post our new articles automatically to facebook. (I use this plugin in another website works well there.)

So the problem is wordpress published some older (from 2014-15) (10-15) article to facebook today. Interestingly this happened last time a week ago 2x times a day.

So where is the problem? and why?

Thank you!