I have a tablestructure like this:
Table entity
(
otherEntity_id int // primarykey
id int // primarykey
parent_id int
)
>
If you are referencing the same column above twice (otherEntity_id) I've seen mappings like this to avoid this sort of error:
References(e => e.Parent).Columns("otherEntity_id", "parent_id")
.Not.Update()
.Not.Insert();
Also when you are running into a problem it is always helpful to show the full error message you are running into.