OMi SM integration causes Duplicate Incident in SM

Hello Experts 

we have an issue at one of our customers , they faces a problem of incident duplication for the same CI , for the incidents opened by the OMi

we troubleshoot the issue and sure that OMi can open and close incidents and SM can sync back to OMi in case of manual resolving 

my questions , if I have all the logs of SM , including the integration log SMOmi what type of errors should I search for , or what could be the reason ?