Why are there 2 air filters on grace?

i have puzzled over this for a long time…harleys have 1 carb on the right side of the engine…hence the round air filter…but when bruce pulls up to the hotel you can clearly see one on the left side also…ive riddin harleys for years and there is absolutely no purpose for it being there…except maybe for semitry…any ideas?

It was Jesse James’ first project ever. He didn’t know shit about Harleys back then.