Should I 301 old URLs to avoid duplicate content and supplemental?

[burtonator]

I have some URLs which are redundant and associated with one main URL that's authoritative. You can view ANY of the URLs and basically get the same page but just with some items slightly reordered.

I'm starting to think that this is really hurting our SEO due to a duplicate content penalty and I want to fix it ASAP.

Here's what I'm thinking.

1. Remove all of these existing redundant URLs from the page moving forward so that only the authoritative URL is shown.

2. All existing URLs which are indexed by google will now become 301 redirected to the main authoritative page.

If I do this retroactively for our existing content will it hurt anything?

If I make this change how soon would I notice a bump? We're talking a lot of content here but for right now I only show up in niche (supplemental?) results.

Thx.

[phranque]

the 301 with a Location header is the correct response for GET and HEAD requests in this situation.
i'm not sure how that will affect your performance in search...