A stringified reference indicates the type and address of that which the original reference referenced. They are unique to the point that references to different entities will have different stringifications. Note however that you cannot get the original reference back from the stringified version; you cannot, for instance, do this:

my $x = 5;
my $y = \$x;
$y = "$y";
$$y = 8;    # Error!  $y is now the stringified form
            # of the reference, and can't be referenced.
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