I noticed the two variations in 2006 and wrote about it on the board. You may be able to find the thread in the archives. Here is the scan I posted:

I noticed the location of the final "E" in Stratosphere as compared to the hot air balloon behind it. I think I noticed something else. I wasn't sure if it was enough for a variation, so I asked on the board. Others spotted other differences. I believe one inlay is larger than the other. Looking now, it looks like the color inside the denomination is a bit different. Anyway, I still have both chips in my collection.

Michael Siskin