I’m afraid that I didn’t explain very well. Every blog using wp-supercache have this problem. Let’s take an example from your blog (https://ocaoimh.ie/2007/11/03/where-have-all-the-wispas-gone/)
I do :
GET /2007/11/03/where-have-all-the-wispas-gone/ HTTP/1.1
(with trailing slash) and I get:
HTTP Status Code: HTTP/1.1 200 OK
Next I do:
GET /2007/11/03/where-have-all-the-wispas-gone HTTP/1.1
(without trailing slash) and I get:
HTTP Status Code: HTTP/1.1 200 OK
This means that you have 2 pages on your blog with 100% duplicate content.
Default behavior of wordpress is to 302 redirect the non trailing slash page to the trailing slash one like in the following example (I will use https://www.onlyaphoto.com/conceptual-photography/horse-power/ because this blog is not using wp-supercache:
GET /conceptual-photography/horse-power/ HTTP/1.1
returns:
HTTP Status Code: HTTP/1.1 200 OK
and
GET /conceptual-photography/horse-power HTTP/1.1 (without trailing slash)
returns:
HTTP Status Code: HTTP/1.1 302 Moved Temporarily
witch is correct.
This way, google will never find 2 pages with the same content.
Please, make your own tests and maybe you can find a fix for this problem. Practically every blog using wp-supercache has this problem.
Thank you