Last modified: 2013-12-17 10:27:31 UTC
Marking a page for deletion results in a posting to user talk page, this triggers two notification: mark for deletion and talk page post.
Prioritization and scheduling of this bug is tracked on Mingle card https://mingle.corp.wikimedia.org/projects/flow/cards/208
Moving to PageCuration component, it should probably use the BeforeEchoEventInsert hook to abort one of the two notifications.