The ref function returns the class name of an object, so you can bless a reference into a class with it,

my $object = Foo->new;
my $fake = bless {}, ref $object;
my $real = (ref $object)->new;
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There is no assurance that Foo's instance methods will work with $fake. Know what your classes are like before you do this.

You can bless a reference into any namespace you like - it doesn't even have to exist in the symbol table.