I have Acrobat DC 2020 (also ran the latest version for 2022 with the same issue. Running the 2020 version as a test to see if the problem presents itself with a different version of the software) installed on my 2012 iMac running macOS 10.14.6 Mojave (currently updating to 10.15 Catalina to see if that solves the issue).
I have a PDF that is my blank contract to writing up my construction agreements. It's pre-typed, just have to fill in the blanks. Well, when I fill in the blank on one page, it duplicates itself on the very next page and places it in the same physical spot on the next page, often laid over the other pre-typed text. It even has it's own text box if I click on it while still in the "Fill & Sign" mode.
So now I have the SAME entry on two pages. If I move the text box from the second page, to the first page, the first page will disappear. When that happens, I move the duplicate box to the blank space where the original entry was. Guess what happens next? A NEW duplicate is now on the next page. 🤬
If I "close" the "Fill & Sign" mode, the duplicates stay. If I close the app and document, it will still
be there if I re-open the PDF doc. If I print the doc, the duplicate is there. If I email the PDF, the duplicate is still present on the PDF for the recipient on THEIR computer.
I had this happen a couple of years ago and I can't figure out how I got it to stop.
I tried deleting Creative cloud and reloading. I deleted Acrobat DC and reinstalled, or atleast tried to. If I tried to install the latest 2022 version of Acrobat DC, creative cloud would attempt to install, run through the percentage of install, I would get a notification on the Mac in the top right corner saying it was installed, but it wasn't. Creative cloud would finish the percentage bar and then the "Install" button would reappear in the Acrobat DC box in creative cloud "All Apps" section. I had to install a 2020 version of Acrobat DC just to get the program to actuall install.
I really don't know what else to do here, anyone else have this issue? This isn't like the issue of copy pasting the box in "edit" mode in Acrobat DC, I don't use that mode since the doc was created by someone else and the text box isn't a copy of the same box elsewhere in the doc, this happens in EVERY text box, and EVERY entry I make no matter where it is on the PDF, no matter the page, no matter if there was a preexisting dedicated text box or I placed my own, it duplicates the same text in the same location on the next page.
The issue is most likely that you're filling in form fields that have the same name. Did you create this file? If so, go to Prepare Form mode and rename the fields so that they are unique. If you're not the creator, report this issue to them and ask them to fix it and send you (and anyone else who downloaded it) a new version.