First of all I'm terribly sorry if there has been a similar thread.

Now, I have a problem with importing an obj object. I've modeled a table in Maya and the table top was modeled like this: first I modeled 1/4 of overall shape and then mirrored the geometry twice (1 - width and 2 - length). Then finished the whole thing. But when I import it to Poser, I can clearly see a distorted edge (don't know if I'm putting this right) where the border between mirrored parts would be. It shows up both in the viewport and in rendered image, with and without texture. I'm fairly new to this and really at a loss. The model is definitely one object and all edges and vertices between the mirrored part have been merged. The topology looks fine, and when rendered in Maya, it looks smooth. 

I'm using Poser Pro 2012 btw. And there's the render of the distorted object rendered without textures. You can notice the vertical edge in the middle. it should have been all smooth.