You mean (I assume) to replicate the mapping of a symmetrical figure? Just mirroring the UV coordinates left-to-right is a simple thing to do in UVMapper, or later versions of the Poser material room, and I guess you know that. I don't know of an easy way to do this. However, if you have UVMapper Pro, you can map one half of the figure, save the template, flip it, then import it as the background image. That will give you something to follow while you're adjusting the other half. A bit of trial and error is usually needed to get the template and the mesh to line up, and you may need to put your finger on the screen a lot. :) Another possibility would be to model one half of the figure and map it; then mirror the mesh and join the two halves together.