If I were you, I'd develop them separately. Bring two developing tanks. If you can't do that, start with the Pan-F since its latent image stability is not as good as Delta. But seriously, with such a wide variation in dev time needed, you are either severely compromising one of the films, or worse yet - both. You could ruin all of the hard work you put into the shooting.
The lesson learned here is probably that it's better to shoot the same film on both occasions.

Good luck!

Quote Originally Posted by DF View Post
Pan F requires 8.5 minutes while Delta requires 12, according to the chart with D76 1:1. I've done Pan F with 10 minutes with good results, but If I bring it up to 12(to "please" the Delta), will it be damaged or just super high contrast? Is there an acceptable compromise between the two? Both rolls are of rainey night shots in the city - wet pavement reflecting lights/Christmas lights/cars zooming by/etc.
Or, should one NEVER EVER attempt such a thing? I'm trying to kill two birds with one stone - since my time slot allows for just one roll/set to be developed.