Simply you can try this out

my %hashMap;

open(FH,"test.txt") or die("Can't open file $! ");

while (<FH>) {
  next if ($_ =~ /^\s*$/);
  my ($key, $value) = /^(.*?)=(.*)$/ or die "Cannot parse $_";
    if($hashMap{$key})  {
        $hashMap{$key}.= ",". $value;
    }else{
        $hashMap{$key} = $value;
    }
  }
    for my $word (sort keys %hashMap) {

        print "$word=".$hashMap{$word}. "\n";

    }
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