It's probably the smoothing angle. Anyhow I doubt it's split verices, because Wings' winged edge topology doesn't normally do that. (With maybe the exception of separate material groupings or extracted/cut objects.) Maybe a pic of the model mesh and the render would make it easier to figure out what's going on.

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Barbequed Pixels?

Your friendly neighborhood Wings3D nut.
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There might be something worth downloading.