How to stop numbers converting to date format on copy paste in Excel?
Solution 1:
Select the empty fields (or the entire column), set them to a string format instead of the default value, and do a special paste (available on right-click) with "values only" to prevent a date format from being auto-applied.
(Moving Victor's comment to an answer, as per MSO, as OP and Victor haven't done so in a week)
Solution 2:
Before pasting, select column that will hold the non-date value. Right click. Select 'format cells'. Then select 'text' as the format and click OK.
Now, go ahead and paste, but paste using the 'match the destination formatting' option.