The solution is to add the banner page as a separate document, prior to the other document in the publication.
Use the Show When function to determine which accounts get the banner page and which accounts do not.
The banner page will have a Page X of Y of Page 1 of 1, then the original document will start at Page 1 of 1 itself.
The customer has a document with a fixed number of pages (Y).
On each page, they have Page X of Y in the Footer.
For some accounts, they want to add a banner page to the publication, but they don't want to affect the page count of the original document.
UPDATED: November 16, 2017