As far as I know there is a plug-in (Project Gemini)at http://www.digitalcarversguild.com that may be exactly what you are looking for. I have always just welded the vertices together and built the first side in a shape that would look well with welding. I'm not sure if it really matters what you use for the UV maps since you will mapping both sides anyways. (Linking would just have a little more to map) I personally have not worked with models created for DarkBasic in Carrara