From some unknown version of mod_perl:

my_setenv("NoNe  SuCh", Nullch);
/* force copy of environment */
...
[download]

I suspected it might be related to forking. This seems to confirm it. When forking, the parent and child processes share memory pages until one writes to them. I don't know why one would need to force the one containing the environment to become unshared.

Have you tried asking on the mod_perl mailing list? If you compiled your own mod_perl, you could simply change "NoNe SuCh" to "NoNeSuCh" and recompile it.