Health insurance -- dual coverage questions

We currently have 2 separate health plans for dd. This is something new to me, & I don't have a clue about how coordination of benefits works IRL. The primary plan still lacks $1000 on the deductible. The secondary plan has a $0 deductible. Both are 80/20% plans, & both cover pump/CGM under DME. Can anyone give me an idea of how they'll work for pump supplies? The supplier is running benefits now, but I'm trying to plan ahead for expenses for the next few months.

 

We had duel coverage for a while. After the primary paid out, I had to personally submit the balance to our secondary insurance to receive that benefit for DME. But in doing so, we were covered at 100%. Our primary used Carecentrix as a DME management provider.