For completeness, this value replacement also occurs when iterating over values of an array, and the replacement value can be from a new hash key or a new array element. The following code

my @arr = ("item 1","item 2");
my %h;
foreach my $v (values @arr) {
  print "$v\n";
  delete $arr[1];
  $h{x} = "sneaky hash value"
}

@arr = ("item 1","item 2");
my @arr2;
foreach my $v (values @arr) {
  print "$v\n";
  delete $arr[1];
  push @arr2, "sneaky array value";
}
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produces

item 1
sneaky hash value
item 1
sneaky array value
[download]