the "I and I" also marks a distinktion between the body (that which can be seen) and the spirit. This is reinforced by the similarity of sound between "I and I" and "eye and I".
The expression "I and I" thus expressedly includes all of ones being.
Also it can be used straight of as a possessive pronoun.
"Is tha fe I an I?";
"It belongs to I and I".
I and I plant the corn
Didn't my people before me
slave for this country?
Jah Bob Marley