You can use hash to get unique values like this. And as suggested by MidLifeXis use array ref per each entry.

#!/usr/bin/perl -w
use strict;
use Data::Dumper qw(Dumper);

my (@logins);
my %foo=();
my $fn = 'logins.txt';

open(my $fh, '<', $fn) or die "Could not open file '$fn' $!";
while (my $line = <$fh> ) {
    chomp($line);
    $foo{$line} = [ split /,/, $line ];
}

@logins = values(%foo);
print Dumper @logins;

print $logins[0][0];

exit;
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