gliders are like 2 year olds, imagine giving two of them a lollipop then
walking away. without supervision one would probably think what the other
has is better and take it.
I feed mealworms, the one that finishes first will see if they can take one
away from the others. I usually just have another one ready, or put the container
in front of the one that is finished.
your older one can have more treats, and probably will eat it faster, so I
would just have another treat ready for that one, or I would let one stay in
cage and let the other one sit on my shoulder.
but in the end, food/treat stealing is pretty common.