why doubling the vertexes when playing the game?

i make a statistic about the vertexes of model: the number in 3ds max is 19k. then i exported it into unity,.Then added all the meshes in the unity,and the number of vertexes is 39k. Making me more confuing is that, when i clinked “play”, in status , it showed that the number of vertexes is 80k at most.
i know “hard edge” will increase the vertex number, but why the status show so many vertexes?

do you have a light in?

A double sided shader can also double the vert count, and vertices along UV seams will be doubled too