POP leave mail on server/not leave

Hopefully this will be a simple answer.  My usual MO is to use POP and download and
delete from server when checking mail.  My computer is down so while in fixing mode,
I'm using a 2001 laptop.  I switched that computer to
Mulberry>Prefs>Accounts>Options>Leave mail on server.  So that the newer computer
when fixed will download the current emails.

What I've noticed in this current mode "Leave mail on server," is if I delete an
email in Mulberry, the next checking will download that email again.  Mulberry is
keeping a matching mailbox to what's on the server.  There's probably a second box I
didn't check.?  

Thanks,
MU
Mulberry 4.0.8  
Mulberry from Spring 2002 to present