If a call is queued for multiple CSQs, the one that answered it will be credited with the answer and the others will be charged a Dequeue. Also, if you redirect a call instead of sending it to an agent (think "leave a voicemail" option in most people's hold loops), I believe that Dequeues you from all CSQs you are queued for as well.
This document covers Historical Reporting, but is still mandatory reading for anyone who wants to have a really good understanding of IPCC Express reporting.
http://www.cisco.com/en/US/products/sw/custcosw/ps1846/products_administration_guide09186a00801d6fa3.html