Primary key constraint violation trying to archive requests

While trying to archive requests, the operation fails. The logs show a primary key constraint violation in dbo.ARc_Conversation e.g

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: java.sql.SQLException: Violation of PRIMARY KEY constraint 'Arc_Conversation_PK'. Cannot insert duplicate key in object 'dbo.Arc_Conversation'. The duplicate key value is (17504).|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at net.sourceforge.jtds.jdbc.SQLDiagnostic.addDiagnostic(SQLDiagnostic.java:365)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at net.sourceforge.jtds.jdbc.TdsCore.tdsErrorToken(TdsCore.java:2781)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at net.sourceforge.jtds.jdbc.TdsCore.nextToken(TdsCore.java:2224)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at net.sourceforge.jtds.jdbc.TdsCore.getMoreResults(TdsCore.java:628)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at net.sourceforge.jtds.jdbc.JtdsStatement.processResults(JtdsStatement.java:525)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at net.sourceforge.jtds.jdbc.JtdsStatement.executeSQL(JtdsStatement.java:487)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at net.sourceforge.jtds.jdbc.JtdsStatement.executeImpl(JtdsStatement.java:664)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at net.sourceforge.jtds.jdbc.JtdsStatement.executeUpdate(JtdsStatement.java:1120)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at net.sourceforge.jtds.jdbc.JtdsStatement.executeUpdate(JtdsStatement.java:1073)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at org.jboss.resource.adapter.jdbc.WrappedStatement.executeUpdate(WrappedStatement.java:272)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at com.adventnet.servicedesk.helpdesk.util.WorkOrderArchiveUtil.executeUpdateQuery(WorkOrderArchiveUtil.java:874)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at com.adventnet.servicedesk.helpdesk.util.WorkOrderArchiveUtil.moveDataToArchiveTables(WorkOrderArchiveUtil.java:505)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at com.adventnet.servicedesk.helpdesk.util.WorkOrderArchiveUtil.archiveAndRemoveActualData(WorkOrderArchiveUtil.java:429)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at com.adventnet.servicedesk.helpdesk.WorkOrderAction.execute(WorkOrderAction.java:233)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:484)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:274)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:507)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at javax.servlet.http.HttpServlet.service(HttpServlet.java:697)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at javax.servlet.http.HttpServlet.service(HttpServlet.java:810)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:237)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157)|

[10:06:02:245]|[04-11-2014]|[SYSOUT]|[INFO]|[208]|: at com.adventnet.servicedesk.filter.EncodingFilter.doFilter(EncodingFilter.java:66)|

etc ...

So far it's occurred for every request that I've tried.

We are using build 7929 on MS SQL Server 2008 R2 Service Pack 2. I can supply a trimmed backup upon request.

Thanks

Chris