adduser and defaults groups

["H. S." <greatexcalibur@yahoo.com>]

I recently installed Debian Sid on an Inspiron 5160. I noticed that the 
user I added during the installation (NetInstall CD) was a member of 
various groups: dialout, audio, cdrom, plugdev, etc. But a new user I 
added later using "adduser <username>" command was not. I had to make it 
a member of these groups using the "adduser <username> <groupname>" command.

Was I supposed to use the "--system" option while making the second user?

->HS

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