@hash{@keys} = ('value2') x @keys

##</code><code>##

perl -MData::Dump -e '@hash{(key1,key2)} = ({a=>1, b=>2},{a=>1,b=>2});dd \%hash'
{ key1 => { a => 1, b => 2 }, key2 => { a => 1, b => 2 } }

##</code><code>##

perl -MData::Dump -e '@hash{(key1,key2)} = ({a=>1, b=>2}) x 2;dd \%hash'
do {
  my $a = { key1 => { a => 1, b => 2 }, key2 => 'fix' };
  $a->{key2} = $a->{key1};
  $a;
}