Duplicate tags issue

[realmaverickuk]

I was checking my Google webmaster tools and notice a lot of tag pages showing up as duplicate content. It appears I had it setup to allow both lowercase and uppercase. This means Widget and widget will be 2 seperate pages.

Changing the setting doesn't alter existing tags.

I need to somehow convert all existing uppercase tags to lowercase and then 301 redirect the uppercase urls to lowercase.

I am guessing I'll need a custom mod of some kind?