Several reports, one problem.
WHEN IT HAPPENS
Outages A confusing release A customer contacting through several channels
WHAT TO DO
Identify the common cause, and link them.
WHY LINK RATHER THAN CLOSE
It lets you notify everyone when resolved.
WHAT TO DO WITH THE DUPLICATES
Reply with the same information, and reference the main issue.
WHAT TO AVOID
Closing a customer's ticket as duplicate with no explanation.
WHY
It reads as dismissal, whatever the merit.
WHAT TO SAY INSTEAD
That it is the same issue, what is being done, and that they will be told.
WHAT TO DO WHEN ONE PERSON CONTACTS SEVERAL WAYS
Consolidate, and tell them where the conversation continues.
WHY IT HAPPENS
Usually impatience, which indicates your response time.
WHAT TO CHECK
Whether the first contact was answered.
WHAT TO BUILD
Detection of duplicates by customer and subject.
WHAT TO MEASURE
How many tickets a single issue generates.
WHY
It measures the cost of a defect in support terms.
WHAT TO USE THAT FOR
Prioritising the fix.
WHAT TO RECORD
The relationship between the tickets and the underlying cause.