Different behavior in Outlook 2011 HTML formatting than Outlook 2007 or 2010

We have a standardized HTML signature with graphics that we use in Outlook 2007, 2010 and 2011.  It is also used with Thunderbird by our Linux users. 

In Outlook 2007 or 2010 the graphics in a signature on a new message or a reply are set to Content-Disposition: inline.  

A new message from Outlook 2011 is ok with its signature graphics set to Content-Disposition: inline.  

A reply from Outlook 2011 sets the signature graphics of the sender to Content-Disposition: inline but changes all previous images in the message thread to Content-Disposition: attachment. 

When this behavior occurs it breaks all inline graphics, both signatures and quoted text. The only graphics this does not occur to are those in the reply body of the message thread.   If Outlook 2007 or 2010 for Windows exhibited similar behavior I wouldn't feel like Outlook 2011 had a problem, but it is not emulating its Win32 counterparts. 

When I originally began testing this issue I was looking solely at the signature and graphics within, but after extensive testing this bug applies to all inline graphics in a message thread. This problem has to be affecting all Outlook 2011 users who have images in message threads.