It appears than when selecting a passage that contains a glissando, and alt+clicking to duplicate it results in all the notes being properly duplicated, but the glissandi are duplicated onto the origin instead, effectively drawing them double.
The same thing happens when I use R to repeat a passage which includes dynamics.
Yes, I’m afraid there are a couple of things like this at the moment. A similar problem exists if you have a tie between notes in different voices, it will also not be pasted properly. We aim to correct this problem in the first post-release update.