Lowercase VS. Uppercase Canonical tags?

[GalcoIndustrial]

Hi MOZ, I was hoping that someone could help shed some light on an issue I'm having with URL structure and the canonical tag.

The company I work for is a distributor of electrical products and our E-commerce site is structured so that our URL's (specifically, our product detail page URL's) include a portion (the part #) that is all uppercase (e.g: buy/OEL-Worldwide-Industries/AFW-PG-10-10).

The issue is that we have just recently included a canonical tag in all of our product detail pages and the programmer that worked on this project has every canonical tag in lowercase instead of uppercase.  Now, in GWT, I'm seeing over 20,000-25,000 "duplicate title tags" or "duplicate descriptions".

Is this an issue?  Could this issue be resolved by simply changing the canonical tag to reflect the uppercase URL's?  I'm not too well versed in canonical tags and would love a little insight.

Thanks!

[FedeEinhorn]

That should be an easy fix for your programmer. If your internal links point to pages with uppercase letters in them, then have the canonical tags with the uppercase. Almost always, uppercase and lowercase loads the same content as the rewrite rules use the URL to look on the products using a DB that does not distinguish uppercase & lowercase automatically (in MySQL, you can force the query to do so, but that will be actually more difficult to just change the way the programmed made the canonical tags). You should also redirect the pages that are duplicate to the original ones, if they have uppercase letters (the original) then the lowercase version should redirect to the uppercase one (once the canonical tags are properly set).

From MY OWN PERSONAL point of view, I always preferred lowercase URLs... if that's the case there's a little more coding to do, but you will end up with all URLs in lowercase (for some reason almost all CMS automatically convert uppercase letters to lowercase in a page URL, like Wordpress does).

Hope that helps!

[GalcoIndustrial]

Thanks for the feedback, Federico!  That actually helps a lot and also helps confirm what our programmer has just done (which is changed all the canonical tags to the uppercase URL).  I guess now we'll play the waiting game and see if Google reduces the number or duplicates after it's next crawl.

Thanks again!