Unfortunately, there is no way of doing this within VideoPad.
If you gave each of the clips a random name somehow, then multi-selected them in the clip-list pane and drag-dropped them onto the sequence (or Ctrl+W), then they would be added in alphabetical order.
You can use View->Media Bin->List View and then View->Media Bin->Sort to change to other types of sorting, too, and VideoPad will add them in whatever order they display as.
You could also use keyboard shortcuts to speed up the process, e.g. Click a random clip / select a random bunch, then Ctrl+W to place them at the end of the sequence, then repeat.