There are other sources that confirm he hand carried secret orders for himself.
Reading the link you gave, Porter could have been referring to the original orders signed by Lincoln. These orders were in fact “confidential” and signed by the President. It you have sources, other than Porter, for “secret orders by Lincoln to Porter” would appreciate links to them.
I am trying to grasp your quibble about the difference between "confidential" and "secret." Is there some distinction here that i'm unable to understand?
But while i'm at it, let me post something that reinforces what I have already told you.
WASHINGTON CITY, April 1, 1861SIR:—Circumstances render it necessary to place in command of your ship (and for a special purpose) an officer who is fully informed and instructed in relation to the wishes of the Government, and you will therefore consider yourself detached. But in taking this step the Government does not in the least reflect upon your efficiency or patriotism; on the contrary, have the fullest confidence in your ability to perform any duty required of you. Hoping soon to be able to give you a better command than the one you now enjoy, and trusting that you will have full confidence in the disposition of the Government toward you, I remain, etc.,
A. LINCOLN.