Rows of Data Pasted is not what was copied...or is it ??

In Access 2002, I am trying to do something I have done thousands of times but it is giving strange results today. I have a table in which I am trying to copy and paste 6 rows at a time into the same table. The reason for the copy/paste is that I only have to change one letter in the name and description fields. I have temporarily removed the primary key as usual. When I copy the 6 rows and then paste them, the wrong data (different rows than what I copied) appears in the pasted rows. It gets more confusing because, if I close the table and reopen it, the correct pasted data is there. This is really messing me up. Anyone ever experience this? Thanks!!