Parallel installation of different Lilypond version

[Helge Kruse]

Hello,

I have installed several versions of Liylpond in parallel. That's useful 
if you migrate to a newer version to use it's features. But I can't 
modify all sources at once. That's why I need to install the current 
version while keeping the old.

When I try to install lilypond-2.13.46-1.mingw.exe it requests me to 
uninstall the old version. How can I circumvent this?

Best Regards,
Helge