replies to federated users don't go through if local user with same name exists

I used to use the account 'mrb' on identi.ca. I now use an account 'mrb' on my own server. With some regularity if users reply to mrb from an identi.ca account the notice does not come back to my account on my own server but is put in the notice list of the account on identi.ca.

I can't put my finger on the exact circumstances, but i think it only occurs when the reply-er uses xmpp.

Here's an example:

The original notice with my reply:
http://identi.ca/conversation/46347329#notice-46705125

(notice that 'mrb' is properly linked to mrb@o.mrblog.nl)

The reply of sud)er is here:
http://identi.ca/conversation/45485887#notice-46705739

attached to a totally unrelated notice of me (but the last of the mrb account on identi.ca)

I would have never seen the reply of sud0er if I had not looked at identi.ca