Do you think that Olivia and Orsino deserve the same punishment as Malvolio? If so why?
Scholarly opinion of Malvolio's situation holds that his behavior was vastly different from Orsino's and Olivia's by nature although similar in appearance.
The idea is that Malvolio, as a steward, is an outsider to that which comprises courtly love, whereas Orsino and Olivia are privileged courtiers. As an outsider, Malvolio doesn't know the inner delicacies and subtleties required in making veiled suggestions of love in letters, whereas Orsino and Olivia do know.
Secret coded love declarations were a reality in court life and there was a set of rules that governed these veiled declarations, rules that Malvolio knew only by hearsay, as it were, not because he was one of the privileged class.
As a result, Malvolio violates the protocols and makes love's "madness" an uncouth display instead of a simmering misfortune. This contrasts markedly with Orsino's and Olivia's deportment, which was a display of the courtly simmering misfortune that was requisite.
According to this understanding, then, no, Orsino and Olivia don't deserve the same punishment because theirs was not the same outsider situation, not the same deportment, not the same offense.
For more information about this, read Twelfth Night, or, What You Will By William Shakespeare, written by Jonathan V. Crewe, Dartmouth College (Introduction, xlv to xlviii).