Royal twins (or Royal multiples)

[Principessa]

Special is the case of two of the Yugoslavian twins.

Prince Alexander of Yugoslavia (August 13, 1924) and his first wife princess Maria-Pia of Savoy (Italy) (September 24, 1934) became the parents of two sets of twins:
- prince Dimitri and prince Michael (1958)
- prince Sergius and princess Helene (1963)

The second set should belong to Bourbon-Parma, but Maria-Pia was not quick enough to divorce.  She's certainly fertile though. 

Was Dmitri the one who committed suicide

Nope, when I am correct Dimitri is still live and kicking. He is well know in the world of jewelry.
His twin Michael is an investment executive

Maybe he is the gay one who came out a few years ago.

I believe he is.

[Principessa]

Apparently there already existed a twin in the Danish Royal Family:

The oldest children of Prince Christian (1942-2013), the 1st cousin of Queen Margrethe (son of prince Knud, only brother of Marge's father). Christian is a younger brother of Elisabeth and Ingolf.

Christian married commoner Anne-Dorte Maltoft-Nielsen (1947-2014). Upon this marriage gave up his princely rank and his rights to the throne. Christian became Count Christian of Rosenborg
 
Christina and Anne-Dorte had three children all daughters:

Countess Camilla of Rosenborg (born October 29, 1972)
Countess Josephine of Rosenborg (born October 29, 1972)
Countess Feodora of Rosenborg (born February 27, 1975)

As you can tell based on the birthdates, the oldest two girls are twins.

[editorathome]

Anne-Dorte was extremely pretty.