In $K$ Theory of Operator Algebras, page 144 and a paper by Skandalis, page 35 the $KK$ groups are defined differently:
Both are triples $(E,\phi, F)$ but Skandalis does not require the condition that
$$\pi(a)(F-F^*) \in \mathcal{K}(E)$$
Are the definitions different?
I believe they are equivalent, as given in a paper by Kasparov and Skandalis.