This is absolutely correct. ASL is so deeply different from English that in certain circumstances where it's a priority that a signer's understanding of the topic is clear there can be two interpreters at once. A hearing interpreter who interprets verbatim to a Deaf interpreter (a CDI, or certified Deaf interpreter) who then interprets to the Deaf recipient.

Public broadcasts should absolutely be interpreted to ensure that everyone has access to understanding them.

I encourage everyone to learn more about ASL and to learn a bit of ASL themselves. There are many amazing resources put out by Deaf people to help folks learn.