I have used , but not fully calibrated, a dupe film sold by Photo Warehouse, meant for duping x-rays.

It is blue sensitive only, and has a rather strong blue tint to the film base. It is slow, ie needs plenty of exposure, but processes positive to positive.

It is described as being suitable for Rapid Access development. I am not quite sure what that means outside of the medical/dental field, so I just process it in dilute paper develop for my works so far.

When I calibrate, I use a step wedge in the margin of the exposure to help me guage more definitiely the effect of differing exposure and development regimes, in terms of developers, dilutions, time and agitation effects. Make and keep notes with your negatives.

If you don't have a small setp wedge, try using an old Kodak projection print scale. - It is a crude step wedge in it's own right.

I would suggest that if it is a dupe film, it is a low contrast type of film compared to conventional camera films. Usually for dupes you don't want to gain contrast, but keep what you have. The inherent contrast of the film can be manipulated to some degree by developer dilution , time and agitation.

Your approach of starting with negatives that meet the contrast range requirements of the albumen process then duping would seem to be a good idea as a starting point.

Once you have mastered making enlarged same contrast dupes, then you can incrementally move on to try to expand contrast in the dupe step.
That would let you take a negative developmed to suit silver gelatine and presumably expand it to suit albumen.

I have also fiddled with real x-ray film for enlarged negatives. It is double coated on both sides of the support, so sharp focus is a challenge. Also the surfaces are relatively soft, and liable to scratching in tray processing. It has a heavy silver load, so it exhausts fixer quite quickly. I think mine is blue green sensitive. I have not worked with it much yet.