a poser material room mage here might have a poser solution for ya.

poser isn't meant for making stuff. about everything ya see in poser was made in max,c4d,etc etc main 3D app's

 would help if ya said what version of poser max cad ya using also.

and did u make the blocks n wall or are you just retexturing someone else meshes ? 

anyways sounds like the 2 separate blocks are one peace boolean or something to gather. 

I don't know nothing about cad.

but all the main 3D app's like max,c4d etc work the same

max will have a way to separate them and a mapper in it .

 but the problem in ya .jpg is the uv map.

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Dark Sphere Mage Vengeance