DB<87> p $hash{'Prefix1=A:c:2'}{X}=42 # new entry
42
  DB<88> x \%hash
0  HASH(0x3598330)
   'Prefix1=A:b:1' => HASH(0x35a48e8)    # appears everywhere
      'X' => 42
      'a' => 1
      'b' => 2
   'Prefix1=A:b:2' => HASH(0x35a48e8)
      -> REUSED_ADDRESS
   'Prefix1=A:c:1' => HASH(0x35a48e8)
      -> REUSED_ADDRESS
   'Prefix1=A:c:2' => HASH(0x35a48e8)
      -> REUSED_ADDRESS
  DB<89>