  In this note we show that $\beta'_*$, the $\beta$-function slopes in the
electric and magnetic theories are equal at the corresponding infrared fixed
points. This follows from the scaling of the correlators of the trace of the
energy momentum tensors. The slopes $\beta'_*$ determine the scaling
dimensions. Our paper can be considered as a commentary to Anselmi et al. [1]
-- it proposes an improved derivation not based on a rather contrived
construction by Kutasov et al. [2]. As a byproduct we note that $\gamma'_{Q^*}$
-- the slopes of the matter superfield anomalous dimension -- vanish at both
edges of the conformal window where one of the dual theories is strongly
coupled. Finally, we determine the two-coupling magnetic fixed point at weak
coupling correcting the result of [3]}.

High Energy Physics - Theory;High Energy Physics - Phenomenology