Delete me

As Paul mentioned, it could be the winding rule (could be set differently if one of your objects started out as text).

You could try running the following macro on the combined graphic.

Sub ToggleWindingRuleOfSelectedObjects()
    Dim s As Shape
    For Each s In ActiveSelection.Shapes
        If s.Type = cdrCurveShape Then
            If s.FillMode = cdrFillWinding Then
                s.FillMode = cdrFillAlternate
            Else
                s.FillMode = cdrFillWinding
            End If
        End If
    Next s
End Sub

If this doesn't fix it, I might ask you to send me the file.

Regards,
Hendrik

http://community.coreldraw.com/forums/p/1036/3564.aspx#3564

http://community.coreldraw.com/forums/p/4480/16458.aspx#16458

Hendrik