When you make a circular extrusion you can get that doubling that you describe.
It is easy to fix :
1. In the 3D panel - Select the extrusion material
2. In properties go to Diffuse material and click the small folder - then choose Edit UV properties
3. Change the tile V/Y value from 1 to 0.5
Click OK - job done
Wow - thank you very very much!!! I would never have figured this out myself
You're welcome .
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