Maybe a trip to Debra Dalgleish's site would help:
http://www.contextures.com/xlfaqApp.html#AlreadyOpen

vnomar330 wrote:

When I open saved Excel files (Office 97 Professional Edition), I receive
the following prompt;

"A document with the "same name" is already open. You cannot open two
documents with the same name, even if the documents are in different folders.
To open the second document, either close the document that is currently
open, or rename one of the documents."

After I close the prompt/message, my file(s) operate just fine. I just
receive the "annoying" warning every time I open an Excel file. Any advice
please.

--

Dave Peterson