Comment by Tijdreiziger

> The Dutch apparently do have a double title for doctors, which are also engineers.

I suppose this is technically true, but AFAIK, you'd just use 'dr.', which would imply that you're also 'drs.' or 'ir.' (as you can't be one without also being the other).

Of course, these days, communication is more casual and you'd be just as likely not to use your title. When I was in University, all of my Dutch professors signed their emails with just their name (no titles), but one of my professors from Germany would stubbornly sign all his emails as 'dr. ir. nat. habil.' :D