If two IP Phones are configured with two DNs.
Phone A: Primary DN 1000
Phone B: Primary DN 2000
Phone A and B: Shared DN 3000
All three DNs have associated with Unity Voice Mail. If a caller leaves a message on a DN 3000 which is shared between the 2 phones. little envelope indicator would appear next to DN as well where the message was left, however whenever we delete the message , the little envelope indicator is still on and a message is waiting to be retrieved but there is no message
Just to clarify one point here, the reference was that 3000 may be
set up as an Alternate MWI for another number not an Alternate DN
So for example, lets say you had an account @ 3333 that at one time
was to be checked by the people @ 3000. Under the MWI settings for 3333
there would have been an Alternate/Additional MWI set up for 3000.
3333 > Edit > MWI > Add new (3000)
You would need to find the mailbox where this 3000 had been referenced as
an Alternate MWI and delete that reference.