viewing scheduling calendar problem

[Bill]

When my client types the first name of the attendee she
wants to invite a drop down box appears to give her a
selection of names to choose from. One is the correct
name beginning with the letter "B" and the other is
incorrect beginning with the letter "L". If she chooses
the correct one and tries to go to scheduling it gives her
an error message "Schedule information for some attendees
may not....". If she types the full name in and then goes
to scheduling the calendar appears just fine. If she
selects the "to" button and selects the name from the
global list it works fine. If she selects the "L" name
and goes to the schedule she gets the error message.
Is Outlook linking the "B" name and the "L" name when she
tries to select the "B" name this way. If so how do I get
rid of that association?

Thanks
Bill