IDL4CPP — enum_prefix/enum_postfix required

As far as I understand it enum_prefix/enum_postfix are a way to change the enum mapping but I don't understand why, because the enums itself are added to the enclosing module, so the following IDL is already illegal, red can't be defined twice
scope. For example the following IDL is illegal

enum Colors { red, green, blue };
enum Colors2 { red, green, blue };

See IDL4.2, chapter 7.5.2, search for "Enumeration value names are introduced into the enclosing scope and then are treated like any other declaration in that