Explode Curves problem!

Hi Guys,

I'm using python for rhino currently. When i run the explode command (rs.ExplodeCurves) or when i just normally explode my curve(which is generated from a dupborder command off a surface) the exploded curve becomes segments of lines and not curve anymore. When i check those exploded curves through rebuild command, its degree is 1 and the point counts is 2, so definetely they became a line after exploding. I find this very troublesome as i need them to explode as a curve not segments of lines. 

Does anyone know how to explode and keep the curvature of the curve? I personally think it occurs this way because the curves are generated through dupborder off a trimmed surface.

Any tips? Suggestions!?

Please anyone help me!

Thanks in advance!!!

Guan