Two bath developers put all the developing agent in the first bath and the accelerator in the second bath.(posted 8675 days ago)Film absorbs the developing agent while in the first bath, but almost no development occurs until its put in the accelerator (second bath). development is limited by the amount of developer absorbed in the first bath, so when development is done, there's no more developer to allow overdevelopment.
Advantages of 2 bath develpment: It's simple. It give high quality results. It's impossible to overdevelop. You could under develop, but you'd have to work really hard at it. The developer lasts a long time. No reduction in quality with repeated use.
Disadvantages: you can't expand the development (that is, develop to a higher contrast). If you need higher contrast negatives, use a different developer.
Typically you develop in the first bath for 3 minutes, drain but don't rinse, and develop for 3 minutes in the second bath. Temperature doesn't matter much. Variations in time don't matter much.
I'm currently exploring 2 bath developers, and so far like what I see. I don't know of any web sites, however. Why not just try some and see if you like the results? Diafine is commonly available, and Cachet, I think, makes one also. Other than that, you have to mix your own from scratch. Photographer's Formulary offers one or two divided developer (that's the alternate name for 2 bath) kits.