Need Permalink help

I have been trying to solve a duplicate meta tag problem google told me about (see this post)and have gotten no help on the issue.

So I think I will try a different direction.

I am trying to figure out the best format for my permalinks thinking it may be what is causing my duplicate tag problems.

right now I have : /%category%/%postname%/
and I am wondering if i should lose the “/” at the end? and add “.html” ?

Since there will not be any other files after the blog post title/”postname”

thanks for any input