my $ref1 = ['a','b','c'];
my $ref2 = ['d','e','f'];

my $refref = [$ref1, $ref2];

myfunc($refref);
print $ref1->[0];

sub myfunc {
        my (@list) = @{[@{$_[0]}]};
        print $list[0][0];
        $list[0] = ['1','2','3'];
}