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https://blog.it-kb.ru/2013/03/11/system-center-2012-operations-manager-scom-opsmgr-error-warning-agent-push-install-one-or-more-computers-you-are-trying-to-manage-are-already-in-the-process-of-being-managed/
SCOM 2012 - Ошибка установки агента - One or more computers you are trying to manage are already in the process of being managed