Ticket merging isn't the only thing which needs to be looked at as part of this. Perhaps it is because of my previous employment coupled with the report writing and BI background but Ticket merging is an evil, evil thing if not used properly or for the right reasons. Many of the 'scenarios' which I am hearing merging being used for are not the same as what I would personally deem appropriate. Merging a ticket should, in my opinion, only be used if the same person raises the same issue more than once within a short period of time. If you have multiple people raising the same issue within a short period of time you'd want to implement something closer to the MOD which I uploaded, Ticket Linking. This will allow for an issue which was raised by multiple people to be connected together. This will give you an accurate count of the total number of requests you have received by help topic but will not hide or alter the real stats like merging those requests will or would.
Ex:
Scenario #1: Merging tickets
Ticket Number requestor Topic/ Subject
123456 John Smith Website not loading
223456 Jane Smith MS Word Error
Total Ticket Count: 2
Total # of Open Tickets: 2
Total number of Unique Issues: 2
Scenario #2: Linking Tickets
Ticket Number requestor Topic/ Subject
123456 John Smith Website not loading
--213456 Jonas Smith www.mysite.com(www.mysite.com) not working
223456 Jane Smith MS Word Error
Total Ticket Count: 3
Total # of Open Tickets: 3
Total number of Unique Issues: 2
Both of the above Scenarios are meant to showcase the same data from the same period of time. Scenario #2 is showcasing linking rather than merging and Scenario #1 is showing what many are using merging for.
Rich