I'm interested in why you carry a second wallet for additional items rather than something that can hold more in the same amount of space.
The idea is that this is the stuff I always have on my person. So, that rules out anything I have to carry around, like a bag or something. Another possibility I considered, and haven't completely ruled out, is having some kind of belt carrier for some stuff.
I have a second layer of stuff, which is my "almost-EDC." It is kept in a day pack in my car or wherever it needs to be so that it is reasonably accessible. It includes a full-sized multitool, a PFAK, poncho, gloves, PSK, and other emergency essentials that I don't feel need to be directly on my body all the time.