asterisk users - Sep 2010 - Same extension on multiple servers confusion

Hi,
I have the same extension registered with multiple softphones on 
multiple servers, i.e.

100-local at hostA
100-local at hostB

and on both hostA and hostB I have the extension in extension.conf

exten => 100,1,Answer()
exten => 100,n,Dial(100-local)

When from softphone registered as 100-local at hostA I

call (100 at hostB)

what I see on the softphone on host B is  "100-local at hostB is contacting
you"
and the call gets routed on the local calls context instead of the 
incoming call context. I expected to see "100-local at hostA is contacting 
you" instead.

Is this behavior something that can be avoided? I thought it would be 
normal to have two asterisk's in e.g. two companies serving the same 
extensions...

Thank you,
Matteo