API for dependency creation allow duplicates

I'm testing 1.9.6 on a copy of my 1.8 database, and I have problem with duplicates trigger dependencies.

The trigger deps have been created using the api based on an sql extraction,
some of the dependenceies where hand created before and those apear to be duplicated now.

The trigger dependecy ma have been created in a 1.8.5 or 1.8.6 installation, not exactly sure of the timeline.

The API should not allow creation of duplicates dependencies.

It may be worth checking in other parts of the api that the problem is not present...