Duplicate title tags google

I noticed in my google webmaster tools I am having google show that I have many pages showing duplicate title tags
for example it shows opinel 3 5/8" walnut garden knife as having two duplicate title tag pages
http://www.gatewayknives.com/Opinel-3-5-8-Walnut-Garden-Knife-p675.html
and
http://www.gatewayknives.com/cart.php?m=product_detail&p=675

they are different urls but go to the same page…do i need to fix this? how do i do so? thank you

Yup - that’s a definite duplicate content issue.

Either ensure the internal rewrite rule is using a 301 redirect, or ensure the clean URL is used as part of the rel=canonical link element…

There are two things you can do.

First, the easy step, decide which URL you want to be displayed by search engines. Then, add <link rel=“canonical” href=“preferred URL”> to the <head>.

Second, slightly more complicated, set up a redirect so that anyone going to the non-preferred URL gets automagically redirected to the preferred one.

By doing this, you can ensure that search engines realise that it is simply one page that can be accessed in two different ways, rather than two different pages each competing against each other.

You’d modify you site and delete one of these two Urls or do 301 redirect