From: Sunnyvale, CA (Unite
Without checking with our Engineers in Germany, I can only make a guess. But I think I am close on this though. [:-)]
We have the option for "Continue MultiSession", and when you write to a CD that has previous data on it, it will show up in the Compilation window as "Transparent", and we make the data you drag over "Noticeably" black, so you can destinquish between the two without problems.
So I doubt this is a bug, or a mistake. More than likely done purposely.