Every track shows its version — original, clean, dirty — right on the row, so you can spot originals as you browse Dig.
To pull only originals, use Search: run your search, then filter the results down to the original version. Where a track exists in more than one version, each is listed separately so you grab exactly the one you want.
Search is a Pro feature. On any plan you can still preview and download originals in Dig — you're just scrolling for them rather than filtering.