Comments Randomly Hide Themself

Hey a quick query from spydistrict.com , when a post receives two comments through this plugin at close vicinity to one another time-wise, only one shows even though both are approved from the settings/moderation. When a third one is entered, all three reveal themselves.

Any idea what the issue is, and how it can be fixed? Thanks a ton in advance!

http://ww.wp.xz.cn/extend/plugins/seo-facebook-comments/