Developing HP5+ ASA 800 in ACU 1 135 and 120 use diffent dilution?

[ajax]

I'm going to develop HP5+ ASA800 (135 format) in ACU 1. Development table from ACU 1 shows dilution 1+5 10.5 minutes for 120 format and 1+10 10 minutes for 135 format. The solution for 135 format is 50% weaker than the 120 format. Both format are actually the same film. They should have the same development time. I actually have both 135 and 120 format. Can I just pick one solution strength for both format? Which one should I use 1+10 or 1+5?

I wonder why the development solution are so much different for HP5+. For Delta 100, they have the same dilution and time.

Please help.

ajax