How to work around dbca error "The Oracle system identifier ... already exists, specify another SID"

If you have previously created a database through dbca and saved it as a template for future use, you may see the following error when trying to specify the same SID again:

The Oracle system identifier ... alerady exists, specify another SID

Solution to the problem is to remove the entry for the SID in /etc/oratab

Then click next in dbca, and the configuration wizard will proceed.

Thanks to Elena for pointing this out in her blog.