asterisk users - Jan 2007 - Weird names vs. correct agent's ext.

Hello all!

I've "Queue Log Analyzer" installed 
[http://www.micpc.com/qloganalyzer] to check Asterisk main stats.

There's an option of "CALLS COMPLETED [ALL]" where I can see the 
completed calls that entered any of the queues. There, there's a 
column that displays the extention number of the Agent who received 
each call, for example, it displays:

Agent/202

So I know who that "Joe" which has that ext. got it.

However, sometimes [like on 2% of the records] it displays weid names such as:

Local/202@default-3e29,1
SIP/202-007bc0f0

My questions are:

a. Why??

b. Can I safely assume, eventhough the display is like that for 
whatever reason, that by reading the extention number between the 
line that such agent received such call? For example, in the two 
samples above it says "Local/202@default-3e29,1" and 
"SIP/202-007bc0f0" so I assume agent on ext 202 got the call, is this 
correct?

Thanks for your help.

Best!
Danny