title: Cannot insert duplicate key row in object 'dbo.MSmerge_contents' with unique index
body: <p>We have Merge replication configured between 1 publisher and 12 subscribers all having SQL server 2008 R2</p>
  
  <p>On one of the subscription I am getting below error</p>
  
  <pre><code>Error messages:
  The merge process could not replicate one or more UPDATE statements to the 'Subscriber' because a stored procedure failed to execute. Troubleshoot by using SQL Profiler. (Source: MSSQL_REPL, Error number: MSSQL_REPL-2147200989)
  Get help: http://help/MSSQL_REPL-2147200989
  Cannot insert duplicate key row in object 'dbo.MSmerge_contents' with unique index 'nc2MSmerge_contents'. (Source: MSSQLServer, Error number: 2601)
  Get help: http://help/2601
  </code></pre>
  
  <p>In the error its mentioned that " <code>Cannot insert duplicate key row in object 'dbo.MSmerge_contents' with unique index 'nc2MSmerge_contents'</code>" I checked <code>nc2MSmerge_contents</code> index script but there is no unique constraint specified for the index</p>
  
  <pre><code>CREATE NONCLUSTERED INDEX [nc2MSmerge_contents] ON [dbo].[MSmerge_contents] 
  (
      [generation] ASC
  )WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
  GO
  </code></pre>
  
  <p>Below is the table structure</p>
  
  <p><img src="https://i.stack.imgur.com/830TM.png" alt="enter image description here"></p>
  
  <p>I need to fix this without dropping/recreating the subscription. Can anyone please help</p>