Problems w/ Appointment Requests send to Distribution Lists

We're using Outlook 2002, and here's our scenario:

Our HR department sent out a meeting request for a very important meeting,
and they sent them using three different distribution lists. They didn't
know about expanding the distribution list name on the Tracking tab so that
it shows each individual name, but did notice that beneath the distribution
list names, they were only seeing tracking information for individuals who
had responded to the meeting request (they were being added to the Tracking
tab as they responded). The HR folks were wondering why they didn't see the
names for those who hadn't yet responded.

I went over and expanded the distribution list names, so that each
employee's name is showing on the Tracking tab, and now some names are
duplicated (i.e., those people who were individually listed because they
responded now also have a "not yet responded" listing from where I expanded
the distribution list).

My questions a

1. If the distribution lists had been expanded on the Tracking tab
immediate after the meeting request was sent, then would they still be seeing
the duplicate names, or would the names have been updated "normally" when the
individuals responded?

2. Some employees to whom the meeting request was sent claim that they
received something that looked like a normal e-mail, without response buttons
at the top. We've been unable to go and verify this, but is this possible?
And if so, what might cause it and how could we keep it from happening in the
future?

Thanks in advance for any help or insight you can provide!

Steph