NHibernate multiple joined subclasses and duplicate column names using criteria

Question

Assume we have this entity structure:

Document
- DocumentA
- DocumentB

In base class Document we have fields Id, Name, CreateDate. In joined subclass DocumentA we have fields Book, Pages. And in DocumentB we have Magazine, Pages.

So the problem is when i try to get records with Criteria:

var prj = Projections.ProjectionList();
foreach (var col in selectColumns)
{
    prj.Add(Projections.Property(col), col);
}
criteria.SetProjection(prj).SetResultTransformer(new AliasToBeanResultTransformer(entityType));

So if we have in selectColumns two Pages columns NHibernate will only select data from first one. In fact it even generates SQL query like this

SELECT top 15 
this_1_.Pages as y0_
, this_1_.Pages as y1_
, this_.CreationDate as y2_
, this_.CreationAuthor as y3_
, this_.Name as y4_
, this_.Id as y5_
FROM Document this_ 
left outer join DocumentA this_1_ on this_.Id=this_1_.Id 
left outer join DocumentB this_2_ on this_.Id=this_2_.Id 

Does anyone know how to solve my problem using Criteria? BTW I do not have option to change this structure, in this system user can define his own classes and nested classes.