Peter,

At some stage you may have clicked :-

Window|New window

Giving you a second instance of your file. Try clicking CTRL + W and save
and your mysterious second window should be gone.

Mike

"Peter Green" wrote:

Asmall excel workbook file of 4 small workshorts suddenly started opening
two identical copies the same file at the same time. Open one both open.
Close one both close, modify one both modify. Save to new name and reopen -
two identical files. It does not seem to do any damage but looks odd and is
worrying.
No other files on the workstation appear to be affected.