hard time with Frame Advisor

hi 

i ve put together a simple unity scene to test out mesh optimization suggested by frame advisor, but i am having trouble figuring out how to fix duplicated vert shown in Frame Advisor. also having trouble with ideal mesh BW.

i m using a simple bg plane mesh exported from maya, ensuring no split vert and all clean

and the test scene looks like this, 1 using Unity legacy standard shader, 4 planes (to the upper right) using custom unlit shader

in frame advisor, all 4 plane to the upper right are being recorded as having 1 duplicated vert in the data

and the one using Unity legacy standard shader, did not have any duplicated vert, its using the same mesh from the same FBX import.

the only diff being the vert attr which presumably are pos, vert col, uv0,uv1 that are being used in the standard shader, are different from the other 4 draws

at first, i was thinking maybe its because of the float4(pos) + float2(uv) in the unlit shader that maybe causing some padding problem? and that s why there is 4 different version of the unlit shader being used in this test scene. each one trying out an maybe idea to fix this duplicated vert issue.

but, clearly they (the ones to the upper right) are still showing 1 dup vert.

and if i was to set the FBX to mesh compression using high in unity, then build

the dup verts now became 4 instead of 1

now i hav no idea as to how to make sense of this data la.

question:

1. can i get an explaination on how the above could be happening?  how come legacy standard shader got no dep vert on the same mesh?

2. how can i get rid of this dup vert in custom shader? ( this is the most vital question BTW)

3. how is the ideal mesh bandwidth calculated ? float3 + float2 = 20 bytes, how do we come to 316 bytes ideal BW ?