It should be possible, but with some restrictions (depending on your application). If you have WAS ND 8.5.5, then you have Application Edition management feature. Read more details on that page.
If you are on the older version, you will have to change several things during deployment, e.g.:
- context-root of the application
- JNDI EJB binding names
- if other version is using different database - update the JDBC references
- if other version is using additional resources (like queues, qcf) update them also.
Actually, port listening has nothing to do with it, as both application will use same port, but different context-roots.
This of course assumes that application doesn't have hard coded values in it (like context root, jndi names, etc).