A user reported a case where on occasion two distinct build records for a job shared the same build number. (The symlink pointed to the later one, and Jenkins loaded the later one, but this apparently caused problems for the Copy Artifact plugin.) The OOOBM did run, printing to the system log for example

... jenkins.diagnostics.ooom.Problem$Inspector scan
WARNING: Multiple builds have the same number: /.../jobs/.../builds/2014-01-23_09-12-34:#18 vs /.../jobs/.../builds/2014-01-23_15-34-56:#18

yet the older build record (/.../jobs/.../builds/2014-01-23_09-12-34/ in the above example) remained on disk, and no warning was displayed in the OOOBM log.