Masquerade Med-Kits are Bugged
No matter what add-ons you add to the kit, you will never get enough charges to heal yourself twice.
Gel dressing, bandages, Gauze Rolls, it doesn't matter. You can heal yourself once fully but only about 70% the next try.
I have tried this with multiple Survivors.
EDIT: For clarity, I didn't miss any skill checks.