Merge records without merging scores

We are planning to use DemandTools with our Salesforce instance to merge duplicate records, but testing this has shown that the person score is summed in Marketo when the records are merged (causing lots of MQLs that aren't real). Has anyone had any success preventing this from happening?

We thought we could try resetting the non-master record score to zero, so we uploaded a csv with email addresses and casesafe IDs (thinking that field would act as the unique identifier between duplicates), but instead of working it actually changed both casesafe IDs to be the same.

Thanks in advance for help - I've opened a support ticket with Marketo, but always have better luck here.