Let $(M,\otimes,1_M)$ be a monoidal category, and let $M$ be a rigid object of $M$, with left and right dual respectively denoted by $$ \Big\{M^*,~~~ \epsilon_l:M^* \otimes M \to 1_M,~~~ \eta_l:1_M \to M \otimes M^*\Big\} $$ and $$ \Big\{{}^*M, ~~~\epsilon_r: M \otimes {}^*M \to 1_M,~~~\eta_r: 1_M \to {}^*M \otimes M\Big\} $$ respectively (just as in Wikipedia $\epsilon$ denotes evaluation and $\eta$ the coevaluation). Let's assume that we have isomorphisms $f_l:M^* \to M$ and $f_r:{}^*M \to M$. Then do we have the identity $$ (\mathrm{id} \otimes f_l) \circ \eta_l(1) = (f_r \otimes \mathrm{id}) \circ \eta_r(1)? $$ This works for finite dimensional vector spaces, so I have guessed that it works in general. Also, do we have the identities $$ (f_l \otimes \mathrm{id}) \circ \epsilon_l = (\mathrm{id} \otimes f_r) \circ \epsilon_r: M \otimes M \to 1_M? $$