Recently I was checking my Google Webmaster Tools and there were some HTML suggestions about duplicate title tags and meta descriptions on two URLs.
When I checked which URLs are in question I saw that Google recognized two identical URLs as a different ones (one with and one without the ending trailing slash).
I thought this is impossible since WordPress itself takes care of this by automatically adding a trailing slash at the end.
So I started to investigate and figured out that W3TC makes this happen. But on a very specific and unique occasion.
This is what I have found out:
If I clear all the W3TC cache, quickly logout from WordPress, flush the cookies and cache from my browser, and open whichever page on my site without the trailing slash, the redirect will not happen and that page will be cached. If I open the same page but now with the trailing slash at the end, that page will be cached too.
The conclusion: W3TC will cache the URL without the ending trailing slash if a unique first time visitor actually visits that page.
Obviously W3TC .htaccess rules are preventing the wordpress redirection in this rear occasion.
On the other hand it might be a host, theme, or any other specific issue in question.
Can anyone else test this and confirm that it's happening?