Yes, the plural noun 'flocks' is a standard collective noun for two or more groups of ducks.

The collective nouns for ducks are:

• brace of ducks (applies to birds, in general)
• flock of ducks (applies to birds on the ground, in general)
• flight of ducks (applies to birds in the air, in general)
• flush of ducks (a brood)
• badelynge or badling of ducks (applies to ducks on the ground)
• paddling of ducks (applies to ducks in the water)
• raft of ducks (applies to ducks in the water)
• team of ducks (applies to ducks in the water)

The collective noun for teachers is a faculty of teachers.

There are several collective nouns for duck:

brace of ducks (applies to birds, in general)

flock of ducks (applies to birds on the ground, in general)

flight of ducks (applies to birds in the air, in general)

badelynge or badlingof ducks (applies to ducks on the ground)

paddling of ducks (applies to ducks in the water)

raftof ducks (applies to ducks in the water)

teamof ducks (applies to ducks in the water)

flush of ducks