Understanding the unexpected result you're getting will really help you in the future.

use strict;
my (%hash,@array);
$hash{A}='B';
push @array,\%hash;
[download]

I have pushed into my array a hash reference. If I run this in the debugger, I can see the following:

x @array
0  HASH(0x300331c4)
   'A' => 'B'
[download]

Resuming:

$hash{B}='C';
push @array, \%hash;
[download]

But:

x @array
0  HASH(0x300331c4)
   'A' => 'C'
1  HASH(0x300331c4)
   -> REUSED_ADDRESS
[download]

I thought I pushed a different value into the array. I expect two hashes in my array, one with value B and one with C. But that's not what I get. A reference is not a copy of the variable, but a link to that variable. My array contains two references to the same variable, %hash. The first array element reflects the new value in %hash, 'C', and the second just says 'ditto'.

use strict;
my (%hash,@array);
$hash{A}='B';
push @array, \%hash;

my (%hash);
$hash{A}='C';
push @array, \%hash;
[download]

Debugger shows:

x @array
0  HASH(0x30033194)
   'A' => 'B'
1  HASH(0x3015f4e0)
   'A' => 'C'
[download]

This time, I created a new hash variable, so the array contains two distinct references. The first array element is unchanged by my actions.

In this example, it appears I have lost that first %hash by reusing the name. In fact, I can no longer retrieve its values using that name. But the value is preserved by the reference in the array.

Minor update made for clarity.