It's nothing you can really help and can be ignored by you. It has to do with a function being declared with an empty prototype (e.g.
sub foo () {...}) and another with no prototype (e.g.
sub bar {...}) and then having the prototyped one become an alias to the unprototyped one:
sub foo () { return "foo\n" }
sub bar { return "bar\n" }
*foo = \&bar;