Data insertions without my request EF6

My project was created on VS17, it is on the 4.6.1 framework. I use Entity Framework 6 in database first. We switched to VS19 and this is the first time I debugged the project on it.

My pc crashed and showed me a blue screen while I was debugging.
When I restarted the project I noticed that the list I had loaded during the debugging with EF6, and displayed in a datagrid, was reinserted (duplicated) in the database with new id. For each inserted item, the related objects were also duplicated in cascade with new ids, as if the entities were no longer tracked by Entity.
However, to query the database I have to instantiate a new data service and use its methods. No method has been developed to insert or modify all a list. The modification or insertion of my data is only done by selecting an id or an entity.
I don't understand how EF6 has done to insert these items, is it possible that it is because of VS19? An incompatibility with the framework or Entity? Is there a link with the blue screen?

Thanks for your answers.