Guarneri basses

[Joel Larsson]

I read about a 19th-century Italian virtuoso who travalled around Europe with a Guarneri bass. (With detachable neck, of all things.) I know that there has been some copying of the Guarneri model - for instance, Alfred Meyer makes Guarneri copies - but I always thought that it was the same with the Guarneri type models as with Stradivari; a famous maker who didn't actually build any basses, only got them attributed to him in lack of knowledge/for want of money/for convenience, or that any seriously made copies where a violin/cello model was simply adapted to the DB.
Now, this suggests that I was wrong. Are there really some Guarneri made Double Basses in the records?