[Plugin: WordPress SEO by Yoast] Rel="canonical" problem

WordPress version: 3.4.1
WordPress SEO version:

I did this: Nothing

Rel Canonical should always show one link per post. But when I suffix any of my blogpost with a number it the canonical url changed to that one.

e.g. http://www.netrival.com/revised-bsnl-data-plans-2g-3g-prepaid-postpaid/ is a post and when i add some numbers like 567/ or anything the canonical url also changed to that one. (www.netrival.com/revised-bsnl-data-plans-2g-3g-prepaid-postpaid/567/)

The problem is not only with my site but crossed checked on a number or other bloggers’ site.

http://wordpress.org/extend/plugins/wordpress-seo/