I have a shadow excel file (extension ".xls:2") that opens everytime I open
my original file. The original file shows in Windows Explorer as extension
".xls" but when I open it, the extension displays as ".xls:1" and the shadow
copy opens at the same time.

The shadow copy is not to be found anywhere in Windows explorer. I have no
hidden files or extensions and I've searched for "*.xls:2" with none found.

The shadow/duplicate copy mirrors every change made to the original file.