There are many ways to go with this depending on the analytical question you are trying to address.
Yes, analysis becomes complex when you have multiple date fields and you ask a question that involves treating them as one. It helps to have a clear idea of what each row in your data set represents (an individual?, an HR action?). Different questions will work better with differently shaped data sets. It is natural to ask questions about counting people when your data set has one row per person, for example, but it can be messy to ask questions about counting HR actions of the same dataset.
Here is a workbook that addresses (what I think is) your question using Tableau 9.3's UNION feature, to reshape your data to have one row for each HR action instead of one row for each individual. You can get a similar effect by reshaping the data in advance before feeding it to Tableau.
Sometimes it helps to have two Tableau data sources that point to the same database but that show the data at different levels of granularity or shaped differently. Then you can use the datasource most natural for the view you want to create, rather than trying to have one mother-of-all-datasources that you use for every problem.
Test Data Worksheet.twbx 48.1 KB