Procmail as an MDA

In the advanced examples for procmail, it says to add a rule in the
sendmail.cf for each #local rule.  For example, if there is a rule
like:
        R$+                             $#local $: $1                   local 
name

you would add another rule above it like:
        R$+ + $*                $#local $@ $2 $:$1              local arguments

I tried this for all the #local rules but am getting an error for the
following rule:
        R<@> + $*               $#local $@ $2 $: <>             special case 
error msgs

Since I am adding these rules on faith (I have no idea what they mean)
should I just leave this one out?

Also, when I send local mail each recipient is getting multiple copies of the
message, ( one for each recipient in the list ) any idea why?

Dorita Menconi