Negative duplicating film

I want to make B&W contact duplicate negatives to use with an alternative process ( I want to keep master copies of the originals and use the duplicates). Does anyone know if this still exists? Kodak used to make a version called Kodak professional B&W duplicating film SO-132, but it's been long discontinued I think.
I want to make duplicate 5X7, B&W negatives with as little loss as possible, hopefully with a one step process. I very much want to keep the whole process analogue and not go down the digital interneg route. If nothing like this is still made is there any chance of anyone having old stock being available for sale? Would greatly appreciate any input at all with this.

Thanks very much.

Andrew

Here's a link to a tutorial, it's very simple after a couple tests.
Regards
Erik
http://unblinkingeye.com/Articles/NbyR/nbyr.html

I've just started working with x-ray duplicating film, and it's a very straightforward way to make duplicate and enlarged negatives. It's a reversal film that processes in paper developer--so you don't need any special chems or elaborate processing schemes. Plus, you can work under a red safelight. The dupe film replicates the contrast of the original negative. I bought mine on ebay, but Ultrafine carries a wide range of sizes. http://www.ultrafineonline.com/ulcotodufi.html