You are describing a problem that is far more common than most spreadsheet users realize. The issue isn't your copying technique or a glitch in Excel's paste function. It is a fundamental mismatch between how Adobe renders structured content and how a spreadsheet expects to receive it. When the first page pastes cleanly and the second page does not, the fault lies with inconsistent data encoding within the source document, not with your workflow.
Let's look at what is actually happening. Your first page likely uses a clean table structure under the hood, with each piece of data assigned to a distinct cell boundary. When you paste that into Excel, the application recognizes those boundaries and maps them directly to your target cells. The second and subsequent pages, however, are probably formatted as double-spaced text blocks inside a single visual cell. Adobe interprets that visual spacing as line breaks rather than column breaks. So when you copy that block and paste it into Excel, it treats every line as a new row. You end up with three or four rows of data where you expected one row. That is the triple-up effect you are seeing.
The practical fix is to change your source before you paste. Instead of copying directly from the PDF viewer, copy the content into a plain text editor first, Notepad, TextEdit, or any tool that strips formatting. That will convert your double-spaced text into a single string of characters. From there, you can use Excel's Text to Columns feature under the Data tab, choosing "Delimited" and selecting "Space" as your delimiter. This will split each word into its own column. Then you simply select the three cells you need and merge them back into a single cell using the CONCATENATE function or the ampersand operator. It takes about thirty seconds once you know the pattern.
This is not a workaround. It is the correct approach for handling documents that were not designed for data extraction. The real takeaway here is that your time is too valuable to spend troubleshooting a paste routine. A tool that forces you to fight with formatting inconsistencies is not serving you. We believe the future of data work should let you import exactly what you need, from any source, without manual cleanup. Until that becomes the standard, the method above will give you control back. Try it on your next page and see if the result matches the single cell you want.