Microsoft says no. The named instance should technically not be listening on port 1433. If both instances are set to listen on the static port 1433 and it's working then maybe something in the cluster environment is allowing it. I'd be a little skeptical of it myself.
We've actually had 3 instances running SQL 2005 in a Windows 2003 cluster for about 3 years using the default port settings and have had no issues at all. When running normally, we are running 2 instances on one node and 1 instance on the other and the failover has worked flawlessly as well.
Microsoft says no. The named instance should technically not be listening on port 1433. If both instances are set to listen on the static port 1433 and it's working then maybe something in the cluster environment is allowing it. I'd be a little skeptical of it myself.
We've actually had 3 instances running SQL 2005 in a Windows 2003 cluster for about 3 years using the default port settings and have had no issues at all. When running normally, we are running 2 instances on one node and 1 instance on the other and the failover has worked flawlessly as well.