First we will create a template from the existing database

environment details

source db - troy
source server - oel6-node01.localdomain
listener port - 1521
user - sys
password - oracle

once you run below command you will get the template in $ORACLE_HOME/assistants/dbca/templates folder with name troy_template

dbca -silent -createTemplateFromDB -sourceDB oel6-node01.localdomain:1521:troy  -sysDBAUserName sys -sysDBAPassword oracle -templateName troy_template

Now we will create database from this template.

dbca -silent -createDatabase -templateName troy_template.dbt -gdbname troy_new

while creating database make sure you change this parameter value from the template

initParam name=”dispatchers”

otherwise you will see this error message

ORA-01081: cannot start already-running ORACLE - shut it down first
ORA-01081: cannot start already-running ORACLE - shut it down first

for my env i removed this parameter from template as it can be added later if needed.