I have five light modules/switches that are all set to turn on at one hour before sunset and two sets of two each at different times off at the same time at night. This is in AHP with timers residing on my CM15a. They have operated flawlessly this way for 13 years in this house. When turning on, the light go on and then dim to set brightness in order of module number (i.e.: A1 goes on, dims, A2 goes on, dims, etc, etc) When turning off, all set to go off at the specified time go out simultaneously. What this tells me is that with dimming setup, the codes are sent individually: A1 on, A1 dim, A1 dim, A2 on, A2 dim, A2 dim, etc and that simultaneous off codes are sent in groups: A1, A2 Off.
I assume then that the ON codes you are sending are just as described and setting them one minute apart would avoid collisions