3351358 - dump ITAB_DUPLICATE_KEY in program /IWBEP/CL_MGW_EXPAND_NODE

Run GET for a redefined "Odata Service (SAP GW)" hit dump: 

Runtime Errors ITAB_DUPLICATE_KEY  
ABAP Program /IWBEP/CL_MGW_EXPAND_NODE 

dump code:

   75 *-check and add simple properties
   76     IF mt_properties IS NOT INITIAL.
>>>>>       lt_properties = mt_properties.       
   78       LOOP AT mt_properties REFERENCE INTO lr_property.
   79         ls_component-name = lr_property->*-property- 

While doing debug,  mt_properties has duplicate record, more than one SAP__ETAG as value in mt_properties key - technical name

SAP Gateway

SAP__ETAG, lt_properties = mt_properties., ITAB_DUPLICATE_KEY, /IWBEP/CL_MGW_EXPAND_NODE, mt_properties, lt_properties , KBA , OPU-GW-COR , Framework , OPU-BSE-SDE , SAP Data Enablement , Problem