Guns and cannons sometimes have two barrels (de dos cañones). So, Mr. Putin enjoys shooting and owns a double-barrelled rifle.
Some mortals, especially in England, have “double-barrelled” (compuesto) names.
Such names are often linked by a hyphen. Such hyphened names are a problem for the bureaucracy in Spain: the systems do not recognize such compound names with a hyphen, although 2 surnames are common in Spain.
So do you have a double barrelled name? Probably. Is it hyphenated?