One FBX assets has differences both in PC and Mac

Hi all, what mess me up is my PC and Mac has same Unity version 2017.4.5f1, but the same fbx asset has different vertex count and one is broken lightmap.

Does anyone met it before? Thank you.

Left is MAC, right is PC, and I bake lm in mac

3552867--285833--upload_2018-7-4_13-36-50.png
3552867--285834--upload_2018-7-4_13-37-5.png

Fixed, for anyone who is interested in this issue or googled this post, just turn off the “Weld Vertices” on Model Importer Inspector.