Below is a class mapping for a legacy database (so I can't change the schema). Reading/hydrating the class instances appears to be working perfectly. However, inserting new instances is generating bad SQL - SQL Server complains about duplicate columns in the INSERT command. Seems like a bug. Does anyione have any suggestions for fixes/workarounds?

BTW, I tried tusing NH 2.0 Alpha1, and it also failed, but in a different way (it tried to set the value of the 13th query parameter when the query only had 12 parameters).

Hibernate version:
1.2.1

Mapping documents:

<class name="Milestone" table="ACMILESTNX">
<cache usage="read-only"/>

<composite-id>
<key-many-to-one name="Activity" column="ACTIVITY"/>
<key-property name="MilestoneId" column="MILESTONE"/>
<key-property name="m_milestoneCat" access="field" column="MILESTONE_CAT"/>
</composite-id>

<discriminator column="MILESTONE_CAT" type="String" length="1"/>

<property name="Description" column="DESCRIPTION"/>
<property name="RDate" column="R_DATE"/>
<property name="Days" column="DAYS"/>
<property name="PercComplete" column="PERC_COMPLETE"/>
<property name="BudgetType" column="BUDGET_TYPE"/>
<property name="BillAmount" column="BILL_AMOUNT"/>
<property name="MilestonePct" column="MILESTONE_PCT"/>
<property name="Status" column="STATUS"/>
<property name="LIndex" column="L_INDEX"/>
<property name="LAtmlxSsSw" column="L_ATMLX_SS_SW"/>

<many-to-one name="MilestoneHeader">
<column name="ACTIVITY"/>
<column name="MILESTONE_CAT"/>
</many-to-one>

<subclass name="RevenueMilestone" discriminator-value="R"/>

<subclass name="BillingMilestone" discriminator-value="B"/>

</class>

Name and version of the database you are using:
SQL Server 2005

The generated SQL (show_sql=true):
NHibernate.SQL: 2008-05-29 15:58:27,136 [4] DEBUG NHibernate.SQL - INSERT INTO lawson.ACMILESTNX (DESCRIPTION, R_DATE, DAYS, PERC_COMPLETE, BUDGET_TYPE, BILL_AMOUNT, MILESTONE_PCT, STATUS, L_INDEX, L_ATMLX_SS_SW, ACTIVITY, MILESTONE_CAT, MILESTONE_CAT, ACTIVITY, MILESTONE, MILESTONE_CAT) VALUES (@p0, @p1, @p2, @p3, @p4, @p5, @p6, @p7, @p8, @p9, @p10, @p11, 'R', @p12, @p13, @p14); @p0 = 'Delete milestone for Jun, 2007', @p1 = '6/30/2007 12:00:00 AM', @p2 = '0', @p3 = '0', @p4 = '', @p5 = '13374.23', @p6 = '0', @p7 = '1', @p8 = '', @p9 = '', @p10 = 'ALA-DIN-CONT ', @p11 = 'R', @p12 = 'ALA-DIN-CONT ', @p13 = '21A', @p14 = 'R'