In our case we work with Oracle 10g with FluentNhibernate and NHibernate .
We have a legacy system based on the db used in our new website .
It means any change on the db may influence the old system.
When we mapped through GeneratedBy.Sequence(“My_Sequence”) , the sequence progressed but it progressed twice – once by NHibernate and once by the trigger on the table.
solution :