  In $2 \otimes 2$, more than 2 orthogonal Bell states with single copy can
never be discriminated with certainty if only local operations and classical
communication (LOCC) are allowed. More than $d$ orthogonal maximally entangled
states in $d \otimed d$, which are in cannonical form, used by Bennett et. al.
[Phys. Rev. Lett. 70 (1993) 1895] can never be discriminated with certainty
when a single copy of the states is provided. Interestingly we show that all
orthogonal maximally entangled states, which are in cannonical form, can be
discriminated with certainty if and only if two copies of each of the states
are provided. The highly nontrivial problem of local discrimination of $d$ or
less no. of pairwise orthogonal maximally entangled states in $d \otimes d$ (in
single copy case), which are in cannonical form, is also discussed.
