I think every situation is different. The typical recommendation is 4 sq ft per bird in the coop and 10 sq ft outside as was said BUT since yours free range all day on quite a large area and they are automatically let out as opposed to waiting on you to open the door, I think they are fine in your coop. Although I am not sure I would add more. Or if possible, can you add to the original coop? What will likely happen is they will all pile into one coop.
The space recommendations are important but I think they apply more to confined birds. Your birds have quite a large area.
My birds on the other hand are confined so I follow the space suggestions.
Right now they're just in a 3x3 (and that includes nest boxes) coop kit from
TSC and a 6x12 dog kennel run. It is way too small for 8 but worked as chicks.
But we are working on, and now have almost finished, a new 4x8 foot coop for the girls and the run will be much larger. I think they will be a lot happier in their new accommodations.
I will also be trying to free range more though.
Yours free range all day so as long as you see no behavior issues, I think they'll be fine
But again I would try to make one larger coop than two coops.
Also one rule you def should follow is one linear foot of roost space per bird.
In winter they may huddle together but in summer they need to be able to spread out