Total File Scan Size Limitations

I have multiple 3Tb external harddrives that I need to check through for duplicates. However, Gemini 2 has a maximum scan limit of 999Gb’s per scan. How can I hook up multiple harddrives and scan through them together when my maximum I need is 12Tb? This is the only reason I didn’t give this app a 5-star rating.

DJOdinn about Gemini 2: The Duplicate Finder, v2.0