Can you use multiple Facebook pixels on one site? The short answer is: yes!
This was a frustrating problem! Before late 2017, Facebook didn’t provide any real documentation about using more than one pixel on a single site. This is hard to believe, as I imagine many businesses work with multiple digital marketing vendors who provide Facebook ad services. From the looks of the many unanswered questions in Facebook’s help forum about this, it’s obvious many were frustrated along with me.