Yes, the equation 2(a+1) = 2a + 2 is an identity. Because, if we substitute any values in the place of “a”, the equation becomes equal.
I.e., 2(1+1) = 2(1) + 2 ⇒ 4 = 4
2(2+1) = 2(2) + 2 ⇒ 6 = 6
2(3+1) = 2(3) + 2 ⇒ 8 = 8, and so on.