hi,
i m new in hibernate, i m trying following code but it throws
org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: [com.yash.appraisal.hbeans.AppraisalHeadDt#com.yash.appraisal.hbeans.AppraisalHeadDt@18f06f[]]

the code i was trying is as follows:
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AppraisalData insertData = new AppraisalData(); // this is parent table

//Head Details
AppraisalHeadDt appraisalHeadDt = new AppraisalHeadDt();
AppraisalHeadDt appraisalHeadDt1 = new AppraisalHeadDt();
AppraisalHeadDt appraisalHeadDt2 = new AppraisalHeadDt();

appraisalHeadDt.setAppraisalData(insertData);
appraisalHeadDt.setAccessMode("V");
appraisalHeadDt.setAppraiserComments("not Done!!!!");
appraisalHeadDt.setAppraiserId("E10");
appraisalHeadDt.setAppraiserRating(4);
appraisalHeadDt.setHeadType("IBP");


appraisalHeadDt1.setAppraisalData(insertData);
appraisalHeadDt1.setAccessMode("V");
appraisalHeadDt1.setAppraiserComments("Done!!!!");
appraisalHeadDt1.setAppraiserId("E10");
appraisalHeadDt1.setAppraiserRating(2);
appraisalHeadDt1.setHeadType("FIN");

appraisalHeadDt2.setAppraisalData(insertData);
appraisalHeadDt2.setAccessMode("V");
appraisalHeadDt2.setAppraiserComments("not Done Properly!!!!");
appraisalHeadDt2.setAppraiserId("E10");
appraisalHeadDt2.setAppraiserRating(1);
appraisalHeadDt2.setHeadType("CS");

Set<AppraisalHeadDt> appraisalHeadDts = new HashSet<AppraisalHeadDt>();
appraisalHeadDts.add(appraisalHeadDt);
appraisalHeadDts.add(appraisalHeadDt1);
appraisalHeadDts.add(appraisalHeadDt2);


insertData.setAccessMode("V");
insertData.setAppraisalFromDate(date);
insertData.setAppraisalToDate(new Date(time_ms));
insertData.setName("XYZ");
insertData.setTimestamp(date);

insertData.setCompId(pk_insert);
insertData.setAppraisalHeadDts(appraisalHeadDts);

HibernateDAO dao = new HibernateDAO();
dao.startNewAppraisal(insertData); // here i m calling save()

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and my HBM file for AppraisalData is as follows:


<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
<class name="com.yash.appraisal.hbeans.AppraisalData"
table="APPRAISAL_DATA" schema="TESTUSER" lazy="false"
dynamic-insert="true" dynamic-update="true">
<composite-id name="compId"
class="com.yash.appraisal.hbeans.AppraisalDataPK">
<key-property name="appraisalId" type="string"
column="APPRAISAL_ID" length="50" />
<key-property name="empId" type="string" column="EMP_ID"
length="10" />
</composite-id>
<property name="accessMode" type="string" column="ACCESS_MODE"
length="1" />
<property name="appraisalFromDate" type="date"
column="APPRAISAL_FROM_DATE" length="7" />
<property name="appraisalToDate" type="date"
column="APPRAISAL_TO_DATE" length="7" />
<property name="name" type="string" column="NAME" length="50" />
<property name="timestamp" type="date" column="TIMESTAMP"
length="7" />

<!-- Associations -->
<!-- bi-directional many-to-one association to AppraisalHeadDt -->
<set name="appraisalHeadDts" inverse="true" cascade="all" fetch="select"
lazy="false" >
<key>
<column name="APPRAISAL_ID" /><!-- a foreign key in APPRAISAL_HEAD_DT referencing the primary key of this table. -->
<column name="EMP_ID" /><!-- a foreign key in APPRAISAL_HEAD_DT referencing the primary key of this table. -->
</key>
<one-to-many
class="com.yash.appraisal.hbeans.AppraisalHeadDt" />
</set>

</class>
</hibernate-mapping>


HBM for AppraisalHeadDt table is as follows:


<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>
<class name="com.yash.appraisal.hbeans.AppraisalHeadDt"
table="APPRAISAL_HEAD_DT" schema="TESTUSER" lazy="false"
dynamic-insert="true" dynamic-update="true">
<composite-id>
<key-many-to-one name="appraisalData"
class="com.yash.appraisal.hbeans.AppraisalData">
<column name="APPRAISAL_ID"></column>
<column name="EMP_ID"></column>
</key-many-to-one>

</composite-id>
<property name="accessMode" type="string" column="ACCESS_MODE"
length="1" />
<property name="appraiserComments" type="string"
column="APPRAISER_COMMENTS" length="500" />
<property name="appraiserId" type="string" column="APPRAISER_ID"
length="4000" />
<property name="appraiserRating" type="integer"
column="APPRAISER_RATING" length="22" />
<property name="headType" type="string" column="HEAD_TYPE"
length="3" />
<property name="timestamp" type="date" column="TIMESTAMP"
length="7" />

<!-- Associations -->
<!-- bi-directional many-to-one association to AppraisalData -->
<many-to-one name="appraisalData"
class="com.yash.appraisal.hbeans.AppraisalData" cascade="all"
lazy="false" insert="false" update="false" >
<column name="APPRAISAL_ID" length="50" />
<column name="EMP_ID" length="10" />
</many-to-one>

</class>
</hibernate-mapping>


can anybody tell me where i m going wrong?
thanks in advance.