How to get the number of pages in the original document?

[berloo-lang]

I encountered a problem when using it. For example, a 2-page document was prepared to be printed twice, resulting in a 4-page PDF file. In other words, the 2-page document was printed twice and duplicated in the PDF file, resulting in 4 pages. However, if the document was only 1 page, this problem would not occur.