mossie four blade props a question

Hi
Some mosquito aircraft with single stage merlins had four blade props.

Now
Mosquito completed four blade props were 12’6′ dia
three blade mossie was 12′ dia
three blade paddle props 12’6″ dia
and the hornet was 12′ dia

So were the mosquito blades a different type ?
or a hornet blade in a large hub ?

I tried checking AP’s but those I checked only refer to the three blade mosquito versions
cheers
jerry