Isn't there at least one confirmed
bass by Nicolo's son, Hieronymous II? Of course, he is considered far inferior to his father as well as to his contemporary, Stradivari, but people aren't always right.
(Especially when it comes to basses... and attributions.)
Thomas Martin makes copies of a Ruggeri double bass, built in 1695, then apparently owned by a Dutch player. Maybe that's the same bass as the one sold to Toronto, or - all the better - there are more than one..?