This is not an easily reproduced condition - it happens every now and then in a development environment I own. Basically under rather heavy load sometimes I will get an error like: "Violation of PRIMARY KEY constraint 'PK__StoredTraceSQL__6A43A4A7'. Cannot insert duplicate key in object 'dbo.StoredTraceSQL'. The duplicate key value is (-9223372036853896059).
The statement has been terminated." In this case, the PK is a bigint with a DEFAULT that's NEXT VALUE FOR a SEQUENCE. If I manually reseed / restart the sequence with the table's MAX value + 1, things start to work again - until the problem randomly happens again in the future.
I know no-one likes the "I can't reproduce it easily", but this is actually happening for me, and I'm hoping perhaps someone else has seen it.