Yes, this is normal. Grouped channels will change automation modes (read, touch, latch, write ..) but not respond to automation on drawn on different tracks.
The best way that I know of to copy automation to another track is to use the command :
Options>Track Automation>Move current/All track automation data to region
This works better if you create a new lane for your aux1 track (Command - M) and create a new region with the pencil tool. Resize it to fit to the length of the automation. Now select the region and use the command above to copy the automation to the region and copy the region to a new lane on the aux2 track.