Reading up on various page improvements as suggested by Google’s Webmaster tools and I’ve come across canonical urls.
Google says to put them on the non-canonical pages. Does anyone know if it hurts a site to have them on the canonical pages too?
For example, for most of my blog posts I make the title a link to the url with the post title and I add a permalink at the bottom using the post ID, in case the title needs changing.
I presume I ought to pick one of these as the canonical url. Should be easy enough to just add to the template and have it pull whichever version of the url I pick in via a template tag. But should I also add a conditional to test that the current page isn’t in fact the canonical page?
I am also unsure whether the url with the title or the url with the id is the best option. One is better for searches, I would guess, whereas the other is guaranteed to never change.