In Hebrew the letters Mem and Beth look a lot like each other. The Beth often is accompanied by a syllabe, a dot that signifies the pronunciation of the letter. A hastily written mem could easily be mistaken for a Beth with such a syllabe. Dubbiel might actually be Dumiel (Hekalot Rabbati 18;6), or Dumael, the silence of God, or the angel of silence (as in death). He is also known as the prince of hell.