Ok, accepted. I thought this was the same situation as in mod_perl usage where you had to be careful with global variables because mod_perl put everything into its subroutine. I forgot that used modules usually have a package statement at the beginning that should solve the problem

and Perl doesn't have any concept of "sub-subroutines"

It is astonishing how easily one is misunderstood on the internet. Naturally perl has no concept of sub-subroutines and that is what I was saying