Can you tel me the process you're going through to produce this bug?
I can't reproduce the problem here either by duplicating the layer, or by copy/pasting the layer.
Is your canvas at a zoom other than 100%?
If your are zoomed in, then ArtRage allows sub-pixel placement of transformed content. If you are zoomed out it may also be placing on a sub-pixel boundary.
If your canvas zoom level is at 100% and your canvas is not rotated at all then you should get pixel-perfect placement of your copied layer.
AndyRage's mantra for graphics engine code:
"Sure - how hard can it be?"