[Evolution] evolution presents three copies of one email message

[jim <jim well com>]

   on an ubuntu 9.04 system, i set evolution to work 
with three different pop email accounts and one imap 
account. 
   it worked fine for two or three months. it recently 
presented three messages for one email message. the 
inbox file showed three messages, each identical with 
the exception of the last two lines, which indicate 
that evolution seems to have copied the message on 
behalf of each of the three accounts. 
   a couple of days ago, it went back to single 
messages, then yesterday back to triplicates, then 
this morning to singles. 
   what to do? 
hopefully, with thanks, 
jim in san francisco