Yes. And our law mentions undivided loyalty in relation to naturalized citizens.
It should be so.
A quite reasonable reading of the state of the law is that nothing precludes formally holding multiple citizenships as long as the individual chooses to be loyal to the USA in every situation where the duties of their various citizenships conflict.
It should be noted that direct conflict in these duties is fairly rare, and usually only arise in wartime, or if an individual seeks a policy-level position in a government.
My point is that loyalty is an intensely personal matter, and the formal holding of multiple citizenships does not mean that someone is de facto disloyal to the United States. It matters more how the person behaves in certain situations.