If that is the case then 12 users it is.  There is a way to create a

default user profile (PMDFLTS.INI file) that gets utilized each time a

user is created.  The details are in a Pegasus Mail Network

Administrators Guide that goes back to v3.2 but I suspect the PMDFLTS.INI file will still work today. 

I attempted to check the pmail.com

website to see if this manual is still available for download but the

site appears to be down.  A Google search shows it available here:  ftp://guam.packet.org/admin.pdf

Seems to be easily achieved though I highly discourage you to pursuit that way. The use of not unique file names has been linked to file corruption and general Pegasus Mail malfunction (in answer to the second part of your question). Creating a dozen of users is not all that hard. Configuring each user's POP & SMTP settings, folders and rules will take a little longer, part of which wouldn't be possible by just copying and pasting.

By 12 mail accounts do you mean that you will be retrieving mail from 12 different hosted mailboxes?  If so I suggest creating 12 identities rather than 12 Pegasus Mail users.  Each identity can be created based on an existing identity so you create the first one then use it as the template for the rest.  You then need only configure a POP3 host for each identity and perhaps the SMTP host for any identity that needs to use a different SMTP server.  You can configure the identities so that they all get checked for new mail or configure them so that some get checked in conjunction with others and some don't.  It's very flexible.  You can then create filters that filter the incoming mail into specific folders.  You ca not have a New Mail folder for each identity though.  Well, you could, but it would need to be named something like NewMail_John and it wouldn't behave like the New Mail folder.

One thing to be aware of is that when working with identities you must be very concious of being the correct identity when doing replies.  Associating identities with specific folders helps with this.  Also, there is an identity selector in the message editor window but changing the identity there will not bring along the default signature associated with the identity you changed to.  The signature will remain the default signature of the primary identity (the one Pegasus Mail is running as).  You can work around this problem by using glossary entries instead of signatures.

I have been working with multiple identities as described above for many years.

No, he wants to peep into other user's accounts (traffic) so they have to be different users, and he will have their mailboxes as external mailboxes of his own. Well, I may have it all wrong but that's how I got the picture. ;)