Combine pages - Why is it now changing the documents I'm trying to combine?!!

I use the combine as PDF option often. I went to try and combine 2 different PDF pages today and it continues to merge the information from one file to another. I just want to take 2 files/pages and make them one file.

There is a pop up message that comes up telling me that it is going to merge my information and if I don't want that than I need to use the portfolio option except when trying it that way, they remain 2 separate files, there is not combining. I don't want to open a "portfolio" with multiple files, I want to open one file that has all my pages in one file where I can scroll through like I used to. This is the most frustrating thing!