The first thing you can not run the same instance with a different port in the single data directory, as we suspect you are trying to run two instances with the different port in the same data directory.
However, you can run two DB instance on the same server using different data directory with a different port, you may face below issue if you are planning to keep two DB instance on the same server.
Application, disk IO performance will decrease
Due to a cause of any disaster both the instance will crash.
Data loss,downtime,data corruption etc..
Thanks & Regards, Shreeyansh DBA Team Phone: +91-9552687400 www.shreeyansh.com