Chinchillas learn habits from each other ... good and bad habits ... I would separate them, if it were me.
Chinchillas chew for various reasons ... one of the main reasons is stress.
Is this a new chinchilla?
Is there a radio or t.v. being plaid loudly?
Are there kids running and playing? Squealing, laughing, crying, fighting?
Has there been a recent food change?
Have you moved the cage to a different location (even if in the same room)?
Do the chins eat side by side?
Do they play together?
Snuggle together?
How often do you give them a dust bath?
Are they eating a normal amount of food?
Is there a new pet in the house?
How long have these two chinchillas been housed together?
What brand Chinchilla Feed are you giving them?
What treats are you giving them?
Do they have wood chew blocks in the cage at all times?
Do they have a lava stone in the cage?
Do they have hay in the cage at all times?
All of these questions and their answers are important.
Jo Ann