I imagine there is some module out there that does it, but writing a general purpose routine to convert an array of key-value pairs into a hash of arrays (HoA) is less than 10 lines of code:

use strict;
use warnings;

sub convertKeyValueArrayToHash {
  my ($aData, $sKeyName, $sValueName) = @_;
  my $hData={};
  foreach (@$aData) {
    my $k = $_->{$sKeyName};
    my $v = $_->{$sValueName};
    push @{$hData->{$k}}, $v;
  }
  return $hData;
}
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And a working demo:

# ------------------------------
# Demo
# ------------------------------

my $var = [
 {
  'city' => 'New York',
  'name' => 'Bill'
 },
 {
  'city' => 'New York',
  'name' => 'Ronald'
 },
 {
  'city' => 'Boston',
  'name' => 'George'
 }
];

use Data::Dumper;
my $hData = convertKeyValueArrayToHash($var,'city','name');
print Dumper($hData), "\n";
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