This conversation thread was about a specific defect (#423386) with Tableau Server 9.0.4. If you are not using that version of Tableau Server and are not using Excel, this is likely a separate issue. I would suggest making a new post with your issue or opening a case with Tableau Technical Support: http://www.tableau.com/support/request
For reference, this specific defect was resolved as "by workaround" meaning the code will not be adjusted since the workaround is a valid solution. See Doug's comments above for the workaround.
Additionally, for some background on this issue:
What is happening with each “tabcmd get” is that the workbook's Excel file is being unzipped into a new Server temporary directory, even if there's an identical Excel file previously unzipped in another temporary directory. With different directory names, the ProtocolPool doesn't match up to a protocol that is using an duplicate Excel file, and thus a new entry is put into the ProtocolPool and a new tabprotosrv is spun off to access the just unzipped Excel file.
When a view is accessed normally through a browser (without tabcmd's required .png or .pdf suffix in the URL), Server is able to match up to an existing protocol to the Excel file in the ProtocolPool. And if on the browser you add a .pdf or .png suffix, the same thing happens as if you were using tabcmd – a duplicate Excel file is unizpped for a new connection and entry in the ProtocolPool
Thanks and hope this helps!
per Nathan's comment, I am going to lock this thread to prevent others from contributing responses that may be a new different issue worthy of a new thread or a support case.