You can create an environment in which multiple versions of WebSphere Application Server can run independently on the same system at the same time. A major consideration in coexistence is the avoidance of port conflicts.
Coexisting, as it applies to WebSphere Application Server products, is running a new release of a WebSphere Application Server product on the same machine at the same time as you run an earlier release or running two installations of the same release of a WebSphere Application Server product on the same machine at the same time.
This article discusses which coexistence scenarios are supported.