My search of the Internet seems to reveal that he was quoting himself.
Note the dates of the following two passages:
Whether those ties shall be organic or conventional, the destinies of Cuba are in some rightful form and manner irrevocably linked with our own, but how and how far is for the future to determine in the ripeness of events. Whatever be the outcome, we must see to it that free Cuba be a reality, not a name, a perfect entity, not a hasty experiment bearing within itself the elements of failure
. Our mission, to accomplish which we took up the wager of battle, is not to be fulfilled by turning adrift any loosely framed commonwealth to face the vicissitudes which too often attend weaker States whose natural wealth and abundant resources are offset by the incongruities of their political organization and the recurring occasions for internal rivalries to sap their strength and dissipate their energies.
~William McKinley, 3rd Annual Message presented in written form to Congress December 5, 1899
To the Senate and House of Representatives
http://www.polsci.ucsb.edu/projects/pre ... ey3su.html
The peace which we are pledged to leave to the Cuban people must carry with it the guaranties of permanence. We became sponsors for the pacification of the island, and we remain accountable to the Cubans, no less than to our own country and people, for the reconstruction of Cuba as a free commonwealth on abiding foundations of right, justice, liberty, and assured order. Our enfranchisement of the people will not be completed until free Cuba shall "be a reality, not a name; a perfect entity, not a hasty experiment bearing within itself the elements of failure."
~PRESIDENT WILLIAM MC KINLEY
SECOND INAUGURAL ADDRESS
Monday, March 4, 1901
http://blasa.studentenweb.org/basic/pre ... gural.html