Wait a minute….
In TV show production, children’s working hours are limited by law…. the younger the child, the less time allowed.
So a baby or toddler is usually portrayed by twins or triplets, so they can replace one another during the filming of a whole episode.
I didn’t think those legal protections extended to the “actors” in comic strips, though.
I admit to being a bit out of the loop on Batman lore…. Is there some other reason Bruce Wayne is being played by two babies?