I've seen Mail 3.2 do this quite a few times:
As far as I can see, Mail is superimposing the value of the ‘To’ header on the value of the ‘X-Bogosity’ header (from Bogofilter). For no good reason.
I think this next one is telling us that while the Transgaming port of EVE Online to Mac OS X is great news for Mac owners, there are still a few glitches that need ironing out:
Fortunately, docking and undocking cleared the mess.