Is copy number variation dynamic?
Your question could be phrased more specifically to avoid ambiguity, but rephrasing it the way that I suspect you mean it, ("Is there any evidence showing that [the rate of] copy number variation changes over time?"), then yes, there is indeed.

The rate depends on many factors including which mechanism and which organism and which region of the organism's genome and as @Michael wrote, also what scale (et. al.) is under consideration too.

So your assumption that the rate is static should probably be stated explicitly.

Nature Reviews Genetics 10, 551-564 (August 2009) | doi:10.1038/nrg2593