Hmm, this seems to be a trick with bless. At least that's all I can deduce from this snippet:

#!/usr/bin/perl -l
*Bar:: = \*Foo::;
print ref bless{}, "Bar";
__END__
Foo
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Haven't seen anything about this in any of the docs but the behavior is consistent since at least 5.6.1.

Update: Even more curious...

#!/usr/bin/perl -l

sub Foo::j { print "F ",ref shift }
sub Bar::j { print "B ",ref shift }

$a = bless {}, "Bar";
*Bar:: = \*Foo::;
$b = bless {}, "Bar";

print "\$a is type ",ref $a;
print "\$b is type ",ref $b;

$a->j;

Bar::j($a);

*{"Bar::j"}{CODE}->($a);

$b->j;

__END__
$a is type Bar
$b is type Foo
B Bar
B Bar
F Bar
F Foo
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I think there are some compile-time vs runtime considerations that must be made.

Update part 2: As far as I understand it, when you bless a reference, the blessed reference will get a pointer to the stash designated by the string you pass as the second parameter. The blessed reference never actually gets the string passed as the second parameter. What ref actually returns is the name on the stash to which the reference points. Thus since Bar points to Foo's stash, you will always get Foo when you bless with Bar.