If just received second doctoral degree, how does one sign their name at the end of an email or other correspondence. Would it just stay Dr. So and So or be Dr. Dr. So and So?
Depending on the country and local department customs, signing Dr. So and So would be already ridiculous enough. But I don't know of any situation where signing Dr. Dr. So and So wouldn't come out as a show off. I particularly would think very poorly of someone signing their name in this way.
In Germany I have seen the title dres. (for doctores) used for multiple PhDs.