returnRequest triggers two emails to the merchant

I am developing an app that uses the Returns API.

When we receive a return request from a customer, we call the returnRequest mutation on Shopify. The problem is that this mutation seems to trigger two duplicate emails to send to the merchant, and they are complaining to us that this is frustrating (understandably so!). Here’s an example of the duplicate emails:

When searching for Shopify documentation about emails, I only found stuff related to Customer email notifications, but nothing that us developers can do to control what emails get sent to our Merchants. There are no fields related to emails in the Returns API, so it seems like we can’t solve this issue from there.

How can we control/configure email triggers related to Returns for our merchants, and not have them receive duplicate emails?