Final answer:
Haydn often wrote his quartets in groups of two, such as his Opus 33 and Opus 76 quartet collections.
Step-by-step explanation:
Haydn often wrote his quartets in groups of two.
One of Haydn's most famous quartet collections is his Opus 33 quartets, also known as the 'Russian Quartets.' This collection consists of six quartets that Haydn wrote between 1781 and 1782. Each quartet in this collection is a standalone work, but they are often performed together as a set.
Another famous quartet collection by Haydn is his Opus 76 quartets. This collection consists of four quartets that Haydn wrote in 1797. Again, each quartet in this collection is an independent work, but they are often performed together as a set.