Legal Question in Constitutional Law in New Jersey

Constitutional amendments can never be unconstitutional, by definition.

Where two amendments are in conflict, the later one might expressly state that it is intended to supplant the earlier one. The 21st Amendment, for example, ended prohibition by expressly repealing the 18th Amendment.

Where the latter amendment does not expressly address the conflict, the courts would probably have to decide which takes priority. There are several criteria they would assess. They would probably examine what the various senators, representatives and state legislators who voted on it might have said about the conflict. The courts also would generally give a more specific provision priority over one that is broader (thus a ban on burning the flag would trump the more general freedom of speech). They might also give the latter amendment priority over the earlier one. There are other such criteria that the courts would consider.

It's also possible that the courts would give one amendment priority under some circumstances, while giving the other priority the rest of the time. Or they might find a way to interpret the amendments so that they don't conflict after all.