Duplicate data rows randomly appearing

[CarolBarnes]

We have a shared Excel 2007 workbook in which one worksheet randomly has duplicate data rows/lines appearing. Users are sure they are not intentionally entering (copying/pasting) these data rows/lines but rather these duplicates are 'just appearing'. Has anyone else experienced this? If so, what causes it (if not the users themselves)?

[FDibbins]

Hi Carol and welcome to the forum

lines and data dont "just appear" in excel, something has to put it there. Is the data that "just appears" just data, or are there formulas as well?
Does it appear at the bottom of a table? (and i mean a table that you created using insert/table, not just 1 that you made up?)

Is it always the same data, do you have macros running?

It might be easier if we could see what you are working with, and some examples of the errant rows?

[CarolBarnes]

Your response does not surprise me as I've worked with Excel for a number of years. There are no macros running. The lines that are 'appearing': some are lumped together (i.e. one data line duplicated 11 times all in one location) and others are appearing in multiple locations (i.e. one duplicate line, then a couple of other data lines before another duplicate line appears of the one earlier, etc.).
I am not able to share the workbook with you as it contains private information of some of our service's consumers.
The duplicate lines are not necessarily appearing at the bottom of the worksheet either.
I'm wondering if this could be the result of a virus on the one person's computer?