Honestly, I'm not sure. I suspect that the processing is per drive, rather than duplicated/unduplicated, first.
Since I'm not sure, I've opened a request, to ask Alex (the Developer).
https://stablebit.com/Admin/IssueAnalysis/28301
Not currently. It would require a change to both StableBit DrivePool and StableBit Scanner to facilitate this.
My recommendation would be to just evacuate unduplicated data on SMART warnings.