I know having more than <wsa:To> or wsa:MessageID header in your Soap
message is a nono, for any binding of wsa: to the various draft and
final WS-A releases.

But what happens if someone sends your stack a message with multiple
wsa headers in different xml namespaces?

<wsa2005:To />
<wsa2003:To />
<wsa2004:To />

Do stacks
(a) reject it as something explicitly forbidden in WS-A
(b) reject it as something users shouldnt be doing
(c) pick one of the addresses at random and use it
(d) verify that the addresses are all consistent

The spec says "A message MUST NOT contain more than one wsa:To,
wsa:ReplyTo, wsa:FaultTo, wsa:Action, or wsa:MessageID header targeted
at a recipient" but it also declares wsa to be mapped to
http://www.w3.org/2005/08/addressing, and pretends that none of the
drafts ever got implementing in shipping code.

I suspect that outcome (c) is the default one, but I am not convinced
it is the right one...

-Steve