I'm recording in a log table all that is changed in a given table, so this need to know when for example the User to change the status from active to inactive.

With this information I will write in my log table information of which record was changed, by whom and what was the value of old and new.

If I instantiate an object before:

db.Entry(chamados).State = EntityState.Modified;

I can even compare, but this error appears at runtime.

*An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key. *

Podem me ajudar por favor?