Use filters in the smart list of your smart campaign. If you need to get more granular, just create a new static list in your program and upload your specific leads to that list. For those that received campaign#1, download the list to an excel file, delete those names that aren't needed for campaign#2 and reupload to the static list. The only field you need is email address since all of the other data is already in Marketo. Don't worry about creating duplicates - if the lead is already in Marketo, Marketo will just reference the source lead that already exists. Think of "static lists" and "smart lists" as "playlists" and "smart playlists" in iTunes. Same exact approach (since lists never contain the source record - that's stored centrally in the database).