For example; if the failure is the result of a maintenance error because the mechanic was tired, cross and under pressure, did that mechanic also work on the other engine on the same shift, and sign off both tasks?
Since quite some time it is prohibited that same mechanic performs same task on both engines or all 3 hyd. systems etc. (critical systems).It was introduced on ETOPS airplanes, but it is (should be) a norm now for all airplanes in Part-145 maintenance. This policy was followed in several maint. organizations I was dealing with in the past.