3D Extrusion - front same as back but reversed

Hi,

I am creating a 3d extrusion and I have 1 image with text and graphics the correct way round for the front and the back is flipped horizontally.  I have added both of these to the materials from postcard so that the front can be used for the front inflation material and the the back for the back inflation material, they are circular in design as is the 3D extrusion that were fundamentally the same size (in pixels)  However, when I apply the materials both end up being smaller than the extruded shape they are being applied to.  Anyone understand why and how I can rectify this.

Once I have this I want to create a GIF that rotates through 360 degrees.

Thanks in advance for your help.