Write SQL to identify multiple subgroupings within a grouping

I have a program that summarizes non-normalized data in one table and moves it to another and we frequently get a duplicate key violation on the insert due to bad data. I want to create a report for the users to help them identify the cause of the error.

For example, consider the following contrived simple SQL which summarizes data in the table Companies and inserts it into CompanySum, which has a primary key of State/Zone. In order for the INSERT not to fail, there cannot be more than one distinct combinations of Company/Code for every unique primary key State/Zone combination. If there is, we want the insert to fail so that the data can be corrected.

INSERT INTO CompanySum
(
    [State] 
    ,[Zone] 
    ,[Company]
    ,[Code] 
    ,[Revenue] 
)
SELECT 
    --Keys of target
    [State] 
    ,[Zone] 

    --We are expecting to have one distinct combination of these fields per key grouping
    ,[Company]
    ,[Code] 

    --Aggregate
    ,SUM([Revenue])
    
FROM COMPANIES

GROUP BY
    [State] 
    ,[Zone] 
    ,[Company]
    ,[Code]

I would like to create a report to help the users easily identify and correct the data so that there is only one distinct Company/Code combination within a State/Zone. For each distinct State/Zone value, I would like to identify the distinct Company/Code combinations within the State/Zone. If there are more than one Company/Code combinations within a State/Zone, I would like all of the records in the State/Zone to be displayed in the output. For example, here is the sample input and desired output:

Data:

RecordNumber    State   Zone    Company         Code    Revenue
------------    -----   ----    -------         ----    --------
1               CT      B       State of CT     65453    10
2               CT      B       State of CT     65453     3
3               CT      B       Travelers       33443    20
4               CT      C       Cigna           45678    24
5               CT      C       Cigna           45678   234
6               MI      A       GM              48089   100
7               MI      A       GM              54555   200
8               MI      B       Chrysler        43434    44


Desired Output:

RecordNumber    State   Zone    Company         Code    Revenue
------------    -----   ----    -------         ----    --------
1               CT      B       State of CT     65453     10
2               CT      B       State of CT     65453      3
3               CT      B       Travelers       33443     20
6               MI      A       GM              48089    100
7               MI      A       GM              54555    200

Here is the DDL and DML needed to create this test scenario

CREATE TABLE [dbo].[Companies](
    [RecordNumber] [int] NULL,
    [State] [char](2) NOT NULL,
    [Zone] [varchar](30) NOT NULL,
    [Company] [varchar](30) NOT NULL,
    [Code] [varchar](30) NOT NULL,
    [Revenue] [numeric](9, 1) NULL
) ON [PRIMARY]


CREATE TABLE [dbo].[CompanySum](
    [State] [char](2) NOT NULL,
    [Zone] [varchar](30) NOT NULL,
    [Company] [varchar](30) NOT NULL,
    [Code] [varchar](30) NOT NULL,
    [Revenue] [numeric](9, 1) NULL,
 CONSTRAINT [PK_CompanySum] PRIMARY KEY CLUSTERED 
(
    [State] ASC,
    [Zone] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]


DELETE FROM [dbo].[Companies]
GO

INSERT [dbo].[Companies] ([RecordNumber], [State], [Zone], [Company], [Code], [Revenue]) VALUES (1, N'CT', N'B', N'State of CT', N'65453', CAST(10.0 AS Numeric(9, 1)))
GO
INSERT [dbo].[Companies] ([RecordNumber], [State], [Zone], [Company], [Code], [Revenue]) VALUES (2, N'CT', N'B', N'State of CT', N'65453', CAST(3.0 AS Numeric(9, 1)))
GO
INSERT [dbo].[Companies] ([RecordNumber], [State], [Zone], [Company], [Code], [Revenue]) VALUES (3, N'CT', N'B', N'Travelers', N'33443', CAST(20.0 AS Numeric(9, 1)))
GO
INSERT [dbo].[Companies] ([RecordNumber], [State], [Zone], [Company], [Code], [Revenue]) VALUES (4, N'CT', N'C', N'Cigna', N'45678', CAST(24.0 AS Numeric(9, 1)))
INSERT [dbo].[Companies] ([RecordNumber], [State], [Zone], [Company], [Code], [Revenue]) VALUES (5, N'CT', N'C', N'Cigna', N'45678', CAST(234.0 AS Numeric(9, 1)))
GO
INSERT [dbo].[Companies] ([RecordNumber], [State], [Zone], [Company], [Code], [Revenue]) VALUES (6, N'MI', N'A', N'GM', N'48089', CAST(100.0 AS Numeric(9, 1)))
GO
INSERT [dbo].[Companies] ([RecordNumber], [State], [Zone], [Company], [Code], [Revenue]) VALUES (7, N'MI', N'A', N'GM', N'54555', CAST(200.0 AS Numeric(9, 1)))
GO
INSERT [dbo].[Companies] ([RecordNumber], [State], [Zone], [Company], [Code], [Revenue]) VALUES (8, N'MI', N'B', N'Chrysler', N'43434', CAST(44.0 AS Numeric(9, 1)))
GO

This is a hopefully better re-construction of a previous post of mine SQL to return unique combinations of non key columns within a set of key columns where I am trying to help clarify the question and provide a simple working example that readers can use.

Please see this SQL Fiddle:

http://sqlfiddle.com/#!18/d0141/1