For some reason when a user is adding a record, it duplicates it three times.
Why is that happening?
Since there is many How can I remove any records that contains a duplicate in a specific column?
Workflow you can check using SharePoint Designer.
Event Receiver - You can download SharePoint Manager and connect to SharePoint server or you can use below PS script
$site = Get-SPSite -Identity "http://siteurl" $web = $site.RootWeb $list = $web.Lists["ListName"] $list.EventReceivers | Select assembly, name, type
Looks like you have some kind of Workflow or Event receiver can cause this issue.
you can avoid this in future to implement the Uniqueness on the column.
Now to remove the Duplicate values from list, couple of options.
Option # 1
Option # 2
Please try to open this list as access(link in IE) and run this query in access
SELECT Claim.[Claim Number], Count(*) AS Expr1 FROM Claim GROUP BY Claim.[Claim Number] HAVING (((Count(*))>1));