Attempt to write vertex but there is already such a record written

Document ID : KB000007386
Last Modified Date : 17/04/2018
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Issue:

Post upgrade from APM 9.7 to 10.5.1, now seeing the following [WARN] message in the Manager of Manager (MOM)'s IntroscopeEnterpriseManager.log:

[WARN] [AppMapAsyncExecutor-4] [Manager.AppMap] Attempt to write vertex (externalId = INFERRED_SOCKET:SOCKET:abc-vip:1521:abc-vip) at 2017-05-22 17:40:56.091, but there is already such a record written at 2017-05-22 17:41:04.593
[{"name":"agentHostName","value":"nzttsmsdux001","type":"GATHERED","owner":null},{"name":"hostname","value":"abc-vip","type":"GATHERED","owner":null},{"name":"inferredBackendNode","value":"true","type":"GATHERED","owner":null},{"name":"name","value":"SOCKET:abc-vip:1521","type":"GATHERED","owner":null},{"name":"type","value":"INFERRED_SOCKET","type":"GATHERED","owner":null}]
[{"name":"agentHostName","value":"def","type":"GATHERED","owner":null},{"name":"hostname","value":"abc-vip","type":"GATHERED","owner":null},{"name":"inferredBackendNode","value":"true","type":"GATHERED","owner":null},{"name":"name","value":"SOCKET:abc-vip:1521","type":"GATHERED","owner":null},{"name":"type","value":"INFERRED_SOCKET","type":"GATHERED","owner":null}]

Environment:
Application Performance Management 10.x
Cause:

The warning message indicates that agents are trying to add data to the APM Team Center, but the data had already been written. This is usually due to a time zone conflict between the MOM, collectors and Agents.

Resolution:

To address this, make sure that the MOM and all Collectors are using the same time source to synchronize with (NTP). 

Additional Information: