Question How to make sure each fragment for each pixel only rendering once?

i use the `targetCamera.pixelRect = new Rect(0,0,512,512)` to set the screen size of camera as 512*512, and also set a 512*512 renderTarget, but it seems like each fragment for each pixel still had rendering about 4 times( some pixels at edge is less than 4 times)


i'm trying to insert the z position of each fragment pixel into a link list for voxelization, this problem makes my program can't work as what i'm think