Vertex Colors and Broken apart Polys

I’ve been messing around with Vertex Colors to have a shadow effect on some of my models.

As a simple example, lets use a box.

3DsMax sees, or rather only chooses to display 1 vertex when you have a welded model.

As an example, this is how Unity sees a model, minus the exaggerated exploding of the model, so each corner has a set of 3 vertices.

The model on the left is what I would like to have my model look like in Unity, yet when I import it, it shows up like the model on the right.

I have yet to figure out exactly how to do this, when the model is still welded, as it should be, inside of 3DsMax.

A possible workaround I have found, is breaking the model apart, so that i also have 3 vertices inside of 3DsMax in the corners where I need it. This however has me a bit concerned, since I’ve heard this can cause a sort of flickering effect between poly’s. Something like that I would very much like to avoid.

So in the end, I have two questions;

1. Does anyone know about a workaround to baking the vertex colors down inside of 3DsMax, so I can export them into Unity and have them look correctly?
2. Should I be worried if I go with the split poly’s workaround, or is that no longer a problem with the current generation of game engines?

A1. Not me, I’m a coder not a Max user.

A2. Unity will handle it correctly if Max exports it correctly. Unity already handles the 3 vertices in each corner this way. (They have different normals, so they’re considered different indexes.) But accidentally move any of the vertices the slightest in Max and all bets are off.