Weird behavior using the Observer pattern - vb.net

Question

Ok, so I have an application that reads another processes memory. I initially had multiple scanning threads for the various areas I needed to read. This was processor intensive so I decided to go with the observer pattern. All was well except that I am having a weird behavior.
Here is what is happening
I have 2 radars (overlay and mapped) Both have a watcher class that attaches to the memory scanner and is notified on a new list of mobs.
so I open radar 1 (mapped) it attaches it's watcher to the scanner and waits for mob list update notifications
Open radar 2 (overlay). same thing happens and another watcher is attached.
all is well and good so far
Now there are properies on the mobs in the list, one of which is IsFilteredOut. This property is set in the radar code after it receives the list.
Now the weird behavior is that no matter what I do, the second radar to be opened changes all the properties of the mobs in the list of both radars. It is as if I am passing the list by ref, but I am not. I actually create a new instance of the moblist class every time I pass the list.
Here is the notify code. As you can see I create a new instance of the moblist class each pass.
Private Sub NotifyMobListUpdated(ByVal Mobs As List(Of MobData))
If Mobs IsNot Nothing Then
For Each w As Watcher In _watchers
If w.Type And WatcherTypes.MobList = WatcherTypes.MobList OrElse w.Type And WatcherTypes.All = WatcherTypes.All Then
w.MobListUpdated(New MobList(Mobs))
End If
Next
End If
End Sub
This is where it is handled in the Watcher class
''' <summary>
''' IWatcher MoblistUpdated Implementation
''' </summary>
''' <param name="Mobs">The Updated mob list</param>
''' <remarks></remarks>
Public Sub MobListUpdated(ByVal Mobs As MobList) Implements IWatcher.MobListUpdated
Try
PostNewMobList(Mobs)
Catch ex As Exception
End Try
End Sub
Public Sub PostNewMobList(ByVal Mobs As MobList)
_sync.Post(New SendOrPostCallback(AddressOf OnNewMobList), Mobs)
End Sub
Private Sub OnNewMobList(ByVal state As Object)
Dim mobs As MobList = TryCast(state, MobList)
Try
If mobs IsNot Nothing Then
RaiseEvent NewMobList(mobs)
End If
Catch ex As Exception
End Try
End Sub
This error is driving me nuts and any help would be greatly appreciated.
Thanks

Answer 1

I actually create a new instance of the moblist class every time I pass the list.
Which only prevents the list from changing, not the list elements. You'd have to clone the element objects as well. I don't have a clue with radars and mobs do, you might want to consider using Send instead of Post.