There has problem in normal and Z pass when I render with motion blur

[cjswohong]

You see, when I render something with checking motion blur in arnold render setting, there has problem in my normal and z depth pass.

I know that normal and zdepth never apply filter, so I set closest in default.

But it looks problem. When I change filter closest to guausian, it looks work. But that's not correct data.

I want to know why.