At this point, Il Grasso was kind of freaking out, and it probably didn't help when a cop arrested him, saying that he, "Matteo," was wanted for a gambling debt. The cop hauled Il Grasso's ass to jail, where, despite his protests, they wrote his name down as Matteo. All of the prisoners greeted him as Matteo, because of course all of these people were on Filippo's payroll, since he had that sweet sweet dome money.
Il Grasso ended up spending a night in jail, and if Filippo had any sense of morality, he'd have ended it there. But he didn't, because of course the guy who may have invented the alarm clock was a sadistic dick. So the next morning, Il Grasso woke up to Matteo's brothers paying off his debt and taking him to Matteo's house, insisting that they were his brothers all day until they slipped him a potion that Filippo gave them. The, uh, "potion" made Il Grasso fall asleep.
Matteo's brothers carried him to his own home and put him in his bed. Before they left, they messed with all of Il Grasso's carpentry tools, as if someone had been using them and didn't know where they should be put away. The next morning, Il Grasso woke up in his own bed to find his house was a mess. Later that day, the real Matteo showed up and told Il Grasso that he had the strangest dream -- that he was a carpenter!
And since apparently everyone in Florence was willing to go along with the prank, Il Grasso pulled up stakes, left his successful business, and ran away to Hungary to get away from those Italian maniacs.