Cookie Query

I was wondering, in Options>Cookies sometimes there are 2 cookies that are similar in the Cookies on Computer list:

e.g.

internetdownloadmanager.com

www.internetdownloadmanager.com

When adding cookies to Cookies to Keep list, is it necessary to add both or will adding either suffice?

I have a massive Cookies to Keep list, and about 30% are the same site but with www infront of them.

Thanks.

Both (but sometimes it's good to clean sime out because often it's a case of the website changing it cookies' names

Both (but sometimes it's good to clean sime out because often it's a case of the website changing it cookies' names

Thank you :)