use warnings;
use strict;
use Data::Dumper;

my @array;
my %hash = ( abc=>123 );
push @array, \%hash;
%hash = ( def=>456 );
push @array, \%hash;

print Dumper(\@array);
print $array[1]{def}, "\n"; # ok
print $array[0]{abc}, "\n"; # nope! hash was cleared!

__END__

$VAR1 = [
          {
            'def' => 456
          },
          $VAR1->[0]
        ];
456
Use of uninitialized value in print at test.pl line 13.

##</code><code>##

my $lag_detail;
foreach my $line ( split( /\n/, $c ) ) {
	if ( $line =~ m/someregex/ ) {
		if ( exists $lag_detail->{ports} ) {
			push( @{ $self->{lags} }, $lag_detail );
		}
		$lag_detail = { lagid => $lag, lagdesc => $4,
			operationstate => $3, adminstate => $2 };
	}
}

##</code><code>##

foreach my $line ( split( /\n/, $c ) ) {
	my %lag_detail;
	...