I know that it is the latest version 10.2000 edition for AD 2000-Merkblatt B 1.
BUT, I have a question that the times 20 or 40 in these formulas is right or not.
Is there any amendment or errata for this?
No, they are correct to the code. Think about Ro = Do/2. Additionally, I suggest you to check the units that required for the formulas, Factor of 10 is for the unit correction only. I trust this is sufficient.