Here is an example

File Foo.pm:

package Foo;

use strict;
use warnings;

use Exporter;
our @ISA = qw(Exporter);

our $foo = "FOO";
our @EXPORT = qw( $foo );

1;
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File Client1.pm:

package Client1;
use strict;
use warnings;
use Foo;
1;
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File Client2.pm:

package Client2;
use strict;
use warnings;
use Foo;
1;
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File main.pl

#!/usr/bin/perl

use strict;
use warnings;

use Client1;
use Client2;

print "Client1::foo=", $Client1::foo, "\n";
print "Client2::foo=", $Client2::foo, "\n";

#both variables $Client1::foo and $Client2::foo are just other names f
+or $Foo::foo, 
#so the second assignment wins
$Client1::foo = 'CLIENT1';
$Client2::foo = 'CLIENT2';

print "Client1::foo=", $Client1::foo, "\n";
print "Client2::foo=", $Client2::foo, "\n";
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Program output:

Client1::foo=FOO
Client2::foo=FOO
Client1::foo=CLIENT2
Client2::foo=CLIENT2
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I'm actually not sure that this is what you really want to do. Please provide some more details if it is not.