If it was a film developer, it may be one that I posted.

I posted a variation on a Pat Gainer formulation that replaced the pyrocatechol in Sandy King's Pyrocat-HD, 1:1 with hydroquinone.

The recipe worked and produced good stain and tanning, but it had lower activity and the tonal values were not quite equal to those produced by the original Pyrocat-HD formulation (based on blue channel densitometry plus A,B comparison of print densities and tonality).

The formulation was only split in the sense that it was presented as 2 concentrated stock solutions formulated for maximum shelf life - like Pyrocat-HD.