Looking at the banner pic on their main page, they seem to have at least one ISP install of multiple racks in the wild. Also, doing a little reading on how "fill" of the devices works, they talk about doing peer-to-peer filling of appliances located at the same site, which leads me to believe, even if not deploying a full rack, deploying multiple appliances to an ISP site is a relatively normal occurance

https://openconnect.netflix.com/en/peering/