Disconnected (exported) mesh because of vertex paint? I have a model that was imported from an erronous file where each triangle was disconnected from the others.
After "reconnecting" it via removing duplicate vertices and exporting (to .ply with vertex paint) I still have some disconnected pieces along the seam of a vertex paint stroke.

How do I connect these faces to the rest of the mesh?

To make it clear:
Blender has it fully connected but the exported file does not because vertices are split.

The actual problem boils down to: How do I merge the vertex color of a vertex that has differing colors in its incident faces?

Update

To avoid confusion: The mesh is fully connected inside Blender (if I select one vertex and then "select connected", all vertices/edges/faces are selected) after the "remove duplicates". However in the exported file the mesh is disconnected at the vertex paint stroke boundary.
There is a threshold value you can change when working with remove doubles.

There is two ways to change it. Both are (as blender standard) after you use the tool.

So first select all vertices (if you only want to join some, feel free to select a subset).



Now do Remove doubles. Probably nothing will happend because the threshold is way low by default. But in the toolbar (toggle it with T), at the bottom are the options for the last used tool. In this case it will look like this:



Simply change the Merge distance to snap together the desired vertices.



The second way to change this options is to press F6 directly after the tool. This brings up a dialog to do the same. It's a matter of personal taste what method you want to use. They are exactly the same in all other aspects.