wm8650 2.2 calendar syncs duplicate events

[ramcomp6]

hi all
my wife has an 8" wm8650 2.2 froyo tablet and loves it, everything works great except for one nagging problem, when the tablet calendar syncs with google calendar the tablet shows duplicate entries, these show up on the tablet but not on google calendar, she has a gmail account.
the problem is driving us mad, is there a fix or work around.
many thanks