In the CoreUnitStats.xml file, constitution appears as follows:

    <UnitStatType InternalName="UnitStat_Constitution">
        <DisplayName>Constitution</DisplayName>
        <DisplayNameShort>CON</DisplayNameShort>
        <DefaultValue>5</DefaultValue>
        <Description>Determines hit points.</Description>
        <Icon>Health_Icon.png</Icon>
        <Hidden>0</Hidden>
        <BaseSovereignAttribute>1</BaseSovereignAttribute>
        <AffectPerLevelUpPoint>1.0</AffectPerLevelUpPoint>
        <Upgradeable>1</Upgradeable>
        <DefaultValue>10.0</DefaultValue>
    </UnitStatType>

Note that <DefaultValue> appears twice, once with a >5< and then with a >10.0<

Don't know whether or not this would cause any issues...