The SO-132 direct pos. dupe film does an okay job for enlarged negs. There have been numerous incarnations of this film, the latest is SO-132, but Kodak was going to discontinue that this year....they told me last month that it will be in production for another year, and then based on the sales they'll see what happens then. I use this film for making duplicate negs (by contact mostly) of old nitrate based roll film. It is an ortho film, but is very slow...you can actually proof your exposures using Azo, aim for an ISO of around 8 or so. I mostly use DK-50 as my developer (in a tank), but next batch I do I'll probably use my XTOL tank...(posted 8378 days ago)The vendors for the NARA, and some other institutions actually prefer to do negative duping in 2 steps. They make an interpositive, and then contact that to get the working negative. You can get alot more control this way, and the interpositive becomes something of the master neg at this point....it's called a "preservation master". The working negs are "surrogates". I spoke with one of the labs a few months ago when I thought the SO films were history, and the guy I talked to told me that the best duping film was Agfa P330p (which I think is now discontinued as well...I don't know for certain, this is a graphic arts product and there's only one distributor for the US...it's very expensive. An 8x10 box of 50 sheets is close to $200). They use the Agfa film for the interpos., and contact print it to Ilford Ortho Plus Copy film for the neg. Ortho+ is close to the old (discontinued) Kodak Commercial Film. I use ortho+ as a copy film , and you can get alot of contrast control out of that film as well. They gave me some substitutes for films , such as Delta 100 or Plus-X for the interpos. Kodak told me to use Tech Pan as the interpos. and TMX 100 as the neg.
At any rate, the interpositive should be dense, it should look dark on a light table. You need to have all the detail there in the shadows, so when you contact it for the neg, nothing is lost. The dupe negs will be a little dense as well....
You can contact Kodak and ask for densitometer aim points if you're interested, or check out their book (now outdated) "Copying and Duplicating in B&W and Color".
One more thing, I spoke with a rep from Bergger as well. They carry 2 dupe films that are close to the Agfa emulsions P330p, and N330p.
I haven't done any platinum printing, but I think you could probably get more density & contrast control by doing this in 2 steps....