Gif of current behavior:
http://imgur.com/HcS4GSt
When I select multiple files in the browser and drag them onto a pad in Impact, they each go to their own pad. This is expected. However, when I hold shift while dropping the files onto a pad, the dialog changes from "Load samples" to "Add samples", which implies what I thought the behavior would be - loading all the samples into the one pad as separate velocity layers. This would be rather useful, and it appears as though this was the intended behavior, but it's not working.