Entering data into a cell has duplicated it in random cells in the same column

[IncandenzaH1997]

Hi, I'm working on a large spreadsheet for work (not built by me) and I've encountered an issue that I can't quite get my head around. One of the columns in the sheet is Occupation and another Address, some of which had previously been filled out and some of which were still blank. After entering "Marketing Director" into one of the cells in the Occupation column, I noticed later that randomly throughout the sheet, other cells in the Occupation column have also been set to "Marketing Director", filling in some blank ones and replacing ones that I had already filled in. There are no formulae in the sheet, and no obvious shared characterisitcs between the cells that have changed to "Marketing Director" after I entered it into the original cell. The caveat to this problem is that I've now realised that while filling in the cells, it has replaced the "D" in "Director" with the first letter of the corresponding address. For example, the if the address was "Dublin", it would be entered as "Marketing Director", however if the address is "Barcelona", it would be entered as "Marketing Birector" etc.

I've even used the Excel trace dependents feature to see if these random cells are somehow based another cell but there are no links between them. I'm not 100% sure if the cells were filled in immediately after I entered the data into the original Occupation cell, as I only realised that there was an issue the day after. I also can't figure out why it's taking the first letter of the address and using that to replace the first letter of "Marketing Director", especially since there are nearly 30 different variables, and Address and Occupation aren't close to each other in the sheet or linked in any way.

Any help would be appreciated, as I've been trying to figure this out all day! Thanks

 

[RayFrye]

Wild guess here... Have you opened the macro or VBA tab to see if there is some strange code behind the workbook or an individual Worksheet?