I will agree with your concept that having the same variable name(s) should not be used as a thumb rule. The confusion cropped-up as I wanted to use the same name in places where it made more sense rather than having different names in each of the subroutines.

In the below example, I get a session_id and I wanted to use in 3 different ( may be more.. ) subroutines. I felt odd to use different names for session_id in different subs. Hence, I posted the query to the Monks for some help..

#! /usr/bin perl 

use strict;

use warnings;

...
...
# get session id
my session_id = get_cgisessionid();

...
...
sub a( $session_id );
...
...
sub b( $session_id );
...
...
sub c( $session_id );

..

sub a {
    my $session_id  = shift;
    ...
}

sub b {
    my $session_id  = shift;
    ...
}

sub c {
    my $session_id  = shift;
    ...
}
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