Can I install 2nd set of postgresql into the same server?

I am using rental server with root access. The server was initially set up
with postgresql, but the db is used only for the server maintanance.

I could not get connected to the database.

The db was started with -i option. But still, I can not get it connected.

The portnumber should be 5432 as default.

Q1. How can I check to see if postgresql is using port 5432?

I have put PGPORT=5432 at .bash_profile and exported it to make sure it is
using port number 5432. But still I could not get connected.

Here is the part of the program I use.

php3 file has the following code:

<?
 include("gw.conf");
 include("include/admchk.func");
 $conn = @pg_Connect($host,"5432","","",$masterdb);
 if (!$conn) {
  echo "<B>Can not connect to the database.</B><BR>\n";
  exit;
 }
?>

Each time I run this portion, I get the error of not connected to the db.

Q2. Can anyone help me find out what to look for in order to correct this
problem?

Q3. Can I install another copy of postgresql into the existing server?
Another words, can I stall another copy of postgresql which will not
interrupt to the previous set of postgresql?

Thank you very much for your help in advance.

Abraham Lee
AMS