In File::Copy, this is used:

my $from_a_handle = (ref($from)
                     ? (ref($from) eq 'GLOB'
                        || UNIVERSAL::isa($from, 'GLOB')
                        || UNIVERSAL::isa($from, 'IO::Handle'))
                     : (ref(\$from) eq 'GLOB'));
[download]

I'm not sure why both isa 'GLOB' and isa 'IO::Handle' are checked, maybe somewhere there's a package that inherits from IO::Handle, but returns something other than a blessed glob ref (and so would probably have to override most all of the methods)? Or maybe someone was just being redundant :-)