Merge Surface? is it possible?

hi

I am trying to merge two (or even more surfaces) together, so that they become one surface. The surfaces are tangent on all connecting sides and have no trimmed edges. (In fact they are the same) The merge command in Rhino works perfectly, but apparently there is no GH equivalent. OR is there? :-). Trying to get this working I've build a logic which extracts the boundary  edges, joins them for U and V and creates a surface from boundary crv. Well this way I am loosing all internal structure- Does anybody have a better idea? or even a solution?

many thanks!