Content is the same, but that's obviously subjective. The conversations were either all with alex or without, meaning, no reply requests were sent to the pre-alex mail with alex in cc and I haven't split tested.
how about the recipients? If they had an email from you before (part of the 5K set), then might be more open to replying to the second one (in the 2k set) even if Alex was not on cc out of guilt?
Most of the recipients are contacted on relatively regular basis (some daily, some weekly, some monthly).