Open 2 excel files in separate windows

start - run - regedit:

Left column
HKEY_CLASSES_ROOT/Excel.Sheet.8/shell/Open/commend:
Right column {adding (space)"%1"}
Double Click on (Default) and write - "C:\Program Files\Microsoft Office\Office12\EXCEL.EXE" /e "%1"
Right Click on Command – choose "rename" and add something to the name  - for example 2 (commend2).

Left column
HKEY_CLASSES_ROOT/Excel.Sheet.8/shell/Open/ddeexec:
Right Click on the folder ddeexec and choose "rename" and add something to the name  - for example 2 (ddeexec2)

Left column
HKEY_CLASSES_ROOT/Excel.Sheet.12/shell/Open/commend:
Right column {adding (space)"%1"}
Double Click on (Default) and write - "C:\Program Files\Microsoft Office\Office12\EXCEL.EXE" /e "%1"
Right Click on Command – choose "rename" and add something to the name  - for example 2 (commend2)