I’m not seeing that, but let me explain the it in my own terms, here. Assume you do not know much about astronomy, but you know how to identify the “morning star”, namely as the heavenly body that is visible in the East in the morning, and you also know how to identify the “evening star”, namely the heavenly body that is visible in West in the evening. Then you may assume these are different objects, and so, if I tell that the morning star is in fact the same object as the evening star, I have given you some useful information. I could go on to tell you that it is not a star at all, but a planet, in fact the planet Venus, which rises and sets with the sun because it is much closer to the sun than we are. But that is not relevant here. The point is that the sentence “the morning star is the evening star” is informative, it tells you something you could not have worked out from the meaning of the terms alone. By contrast “the morning star is the morning star” gives you no information at all. Given that you know what the morning star is, it is simply an expression of the principle of identity, A = A for all A, which presumably you knew, or would have assumed, already. Thus ‘the morning star’ and ‘the evening star’ have different informational content.
(1) The sentence “the morning star is the evening star” has informational content.What’s wrong with that? We might want to make a few extra assumptions to make it logically watertight. For example, to add the assumption that if all the component parts of two sentences have the same informational content, then the sentences themselves have the same informational content (the compositionality principle). But I don’t see what’s desperately wrong with it as it stands.
(2) The sentence “the morning star is the morning star” does not have informational content.
(3) Therefore, the term “the morning star” does not have the same informational content as “the evening star”.