Question about tuning system

So I was wondering can you put multiple instance of the same perk on a character? For example, dabis white hair outfits default color has 4 slot where you can have mr. compress's max down hp+. Would i be able to unlock and use all 4 at the same time? I haven't put anything into the system because I'm waiting for kiris undefeatable costume (or to pull his festival one) before using my materials.

Also, how much extra hp does the down hp+ thing give?