#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11107038
use warnings;

my %hash;
while( <DATA> )
  {
  my ($prefix, $glob, $value) = split /(?<==)|\s/;
  $hash{$_} = $value for glob $prefix . $glob =~ s/[^:]+/{$&}/gr;
  }
use Data::Dump 'dd'; dd \%hash;

__DATA__
Prefix1=A,B:c,d value1
Prefix2=A:b,c:1,2 value2
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Outputs:

{
  "Prefix1=A:c"   => "value1",
  "Prefix1=A:d"   => "value1",
  "Prefix1=B:c"   => "value1",
  "Prefix1=B:d"   => "value1",
  "Prefix2=A:b:1" => "value2",
  "Prefix2=A:b:2" => "value2",
  "Prefix2=A:c:1" => "value2",
  "Prefix2=A:c:2" => "value2",
}
[download]