Instance name doesn't matter in SSMS

Hi,

We have 2 sql server 2008r2 named instances on the same box. They have different ports, 7001 and 7002. I noticed that when accessing to each of them, instance name doesn't matter. All it matters is box name and the port.

For example, in SSMS we can specify: <box name>\<unexisting name>,7001, and we'll succeed in connection the the first named instance. I find it very dangerous, because if you ad-hoc connect to the instance, and you put the wrong port, you might modify wrong data (in this case, instances hold same databases).

Is there any way that could prevent this?

Thanks,

Pedja

Pedja