splitit is for spell data: It splits overlapping spells within a case and leaves the data otherwise untouched. The resulting file has the fewest possible number of split spells satisfying the condition not to overlap, for a given data set.
combival is designed for exploratory and data preparation purposes: It creates variables that combine the levels of a source variable within a defined group of observations. Thus, information that is spread over several observations is compiled and displayed for each observation of the group.
To get more information or install the ado-files, use stata commands
help splitit help combival
or
ssc install splitit ssc install combival
These two ados, that might be useful if you do data management and data analyses, have been published on ssc by Ralf Künster (NEPS, WZB) and Klaudia Erhardt (SOEP, DIW).