2456732 - Runtime errors "ITAB_DUPLICATE_KEY" in ABAP Program "SAPLAGS_CUSTOM_CODE_API"

In ST22, the following dump is found:

Category               ABAP Programming Error
Runtime Errors         ITAB_DUPLICATE_KEY
ABAP Program           SAPLAGS_CUSTOM_CODE_API
Application Component  SV-SMG-CCM-CDM

Short text                                                                                       
there is already a line with the same key.

What happened?                                                                                   
Error in the ABAP Application Program                                                        
The current ABAP program "SAPLAGS_CUSTOM_CODE_API" had to be terminated because              
it has come across a statement that unfortunately cannot be executed. 
   
Information on where terminated                                                                  
Termination occurred in the ABAP program "SAPLAGS_CUSTOM_CODE_API" - in                      
"AGS_CC_EXTRACT_CCITY".                                                                     
The main program was "SAPMSSY1 ".                                                            
In the source code you have the termination point in line 302                                
of the (Include) program "LAGS_CUSTOM_CODE_APIU39".

lt_h_attrib_data = lt_attrib_data.

SAP Solution Manage 7.1 SP12-SP15.

lt_h_attrib_data = lt_attrib_data, AGS_CC_EXTRACT_CCITY, ITAB_DUPLICATE_KEY, SAPLAGS_CUSTOM_CODE_API, Runtime, ABAP Program. , KBA , SV-SMG-CCM , Custom Code Management , Problem