I am worried about Spelda biting Twig through the bars of the x-pen. Should I wrap cardboard around the other rabbits cage when one of them is running around? Also I want both of them to be able to run around the room for 12 hours a day but would it be better to let them out on 12 hour or 6 hour shifts? Here is what the shifts would be 

12 hour

Spelda 12am-12pm

Twig 12pm-12am

6 hour

Spelda 12am-6am & 12pm-6pm

Twig 6am-12pm & 6pm-12am

It may be fine - I would just see what happens before you put cardboard around and obstruct their views.

I think either shifts are fine - I think you should do what works best for you.

is it a metal xpen? i think a bunny would have a very hard time chewing through those bars, you shouldnt have to worry

Thanks, I guess I did not word that very good. I meant I was worried about Spelda biting Twig when they sniff through the bars because Twig is so small.

oh sorry no that was me not reading it properly, if you want to avoid cardboard could you maybe put a smaller mesh wire on part of the xpen so they can still see/sniff each other?