I would suggest you read these two articles listed as it is the original dual factor and a newer revised edition. I have been doing this workout for awhile now and no where that I know of does it say to increase during your recovery phases.
Taken from the links below:
How Will I Know How Hard To Load And Unload?"
Well, honestly, it's not an exact science. The easiest thing to do is to start this program and load for only one week, and follow it with a one week unloading period. If you felt fine, and never felt like you were overreaching, then try to load for 2 weeks next, followed again by a one week unloading period. If you are still fine, then you could even try loading for 3 weeks, followed again, by just one week of unloading.
I would note, however, that I have found that most athletes do best with a 2 week loading period, followed by a one week unloading period.
For unloading, it's usually best if intensity is kept relatively high. (Intensity is not a perception of how hard you are working, but is a term relating to how close of a % to your rep maximum you are working - therefore, it's important during unloading weeks to still train heavy.)
However, even though intensity is kept high during unloading, volume is drastically reduced, by dropping the workouts from approximately 7 exercises down to only two or three. Frequency (number of training sessions per week) is sometimes reduced, but in this program it's kept the same
part 1
Bodybuilding.com - Matt Reynolds - Dual Factor Training: How To Use Training Theory To Reach Your Physique & Performance Goals.
part 2
Bodybuilding.com - Matt Reynolds - 2FT: Dual Factor Training - The Program.