What you can do is add a "Group by Segmentations" to the Setup of the report (this presumes that you will first set up a Segmentation to identify your two types of leads).
By doing this, the report will separate the two... but it comes with a catch: you won't see a breakdown by email anymore, only by the segmentation groupings. In other words, if your program has five emails, the report would normally show you each email and the stats for each. By adding this segmentation to it, it will combine the results for all of the emails as they relate to each individual segmentation.