After installing a newer version of the program, the HICSOAP shortcut on the Desktop defaults to running the newly installed version. But you can still run the previously installed versions. When you install a newer version, the previous versions are not removed.
All the versions are located in c:\ProgramFiles(x86)\Hic
[needs work, sorry]
Please keep in mind that although it's rare, new versions of the software can modify the basic structure of the database. So it's not always possible to open a database with an older version.