99.9% of the time, if the file being included has no package statement, you want do instead of require. require only runs the included file once, not once per require.

>type 544228.pl
print '!';
>perl -e "require '544228.pl'; require '544228.pl'"
!
>perl -e "do '544228.pl'; do '544228.pl'"
!!
[download]