You can find what listeners are running in Unix by typing the following command.
ps -ef | grep tns
oracle 18873 1 0 Dec12 ? 00:00:00 /u02/app/oracle/product/10.2.0/db_1/bin/tnslsnr LISTENER -inherit
oracle 18876 18873 0 Dec12 ? 00:00:00 /u02/app/oracle/product/10.2.0/db_1/bin/tnslsnr LISTENER -inherit
root 21779 8976 0 08:06 pts/1 00:00:00 grep tnslsnr
Check all listeners returned for the correct listener and stop the undesired listeners. You will need to set your ORACLE_HOME to match the ORACLE_HOME of the listener you want to stop. Then set your ORACLE_HOME for the listener you want use, check current stats (lsnrctl stat), make any necessary changes and type lsnrctl reload to bounce the listener. Any changes you made will take effect at this point.
However, if your login is related to a listener problem you should be receiving some type of TNS error code. If so, on the Unix Command prompt, type oerr TNS <Error Number> to determine what it actually causing you your problems.
If you have two listeners running that means that you have two instances of Oracle running.
What error message are you getting?
two listeners running doesn’t mean two instance of Oracle.
Please specify what error you are getting
If u know which listener you are using then stop another listener using LSNRCTL command
The fact that you have one or two listeners running on a system doesn’t necessarily affect your login problem and certainly doesn’t imply the number of database instances running. Typically a login problem is due to your environment and/or permissions settings. If you are the DBA, you should know if and why more than 1 listener is running. If you are the DBA, then check the listener.ora file and see how the listeners are defined. I have multiple listeners on a system when I have multiple versions of Oracle installed and there are communications compatibility issues…. such as a 7.3.4 listener on a system which also has a 9.2.0 listener. I realize the age, etc issues… but sometimes it is necessary. But the first question must be, what error are you receiving, or is it simply locking and not responding? If you are coming from a client system to the database server, there could be different issues than if you are on the database server trying to connect. But you need to start with the error to determine the problem.