If installing another mod...

[Atraphoenix]

if the mod is subfoldered namely it creates its own folder like EB the is no problem but if the mod overwrites RTW namely is not subfoldered you need a different RTW installation.
in fact I have a different RTW installation for EB also a different for RS and IBFD together.
so long as one of the mod is subfoldered you can play two mods together but it may not be as stable as a pure one mod installation.
but it is impossible to install two mods that overwrites RTW files.