Data group list checks in v11

You can add the two values for the same IP to one entry:

"192.168.1.1" := "fred_jones|Paul_jones"

When you do the lookup, you can split the value on the delimiter and check each sub-value:

http://www.tcl.tk/man/tcl8.4/TclCmd/split.htm

foreach name [split $value "|"] {
   if {$name eq $user_name}{
       ...
   }
}

Aaron