Hi ila_staff.
I am doing some research but haven't found anything yet on Mode G3 or Receive Again.
I have found this information in the product knowledge base: Configure the Machine for Sending or Receiving Faxes and it contains a table with Settings and Specifications but still noting on Receive again.
http://www.support.xerox.com/support/WC6505/support/en_US.html?objGUID=8450
I will continue to research and post what I might find. In the meantime you might want to also search the knowledge base.
http://www.support.xerox.com/support/workcentre-6505/support/enus.html