Why do some aircraft have 4 nosewheel doors?
Having multiple door sections for the nose gear is a common design. Looking closely at the photo below may make the reason more clear:



When the nose gear retracts, it swings forward. You can see that the wheels will need a larger opening than the narrower strut. So instead of having one door with a strange shape or that is larger than it needs to be, it is split into two sections. This also allows the forward doors to be closed once the gear is extended, which reduces drag.

Splitting the doors down the middle allows for symmetry, and it reduces the amount of surface area each hinge or actuator must support. This results in 4 separate door sections.

Looking at the main landing gear, you can see it uses a similar design. For example, the outboard gears swing inwards on retraction. The doors that cover the main gear bays are larger, and are only open during extension or retraction, and are otherwise closed. The smaller doors at the locations of the struts remain open.