No, a passive imperative doesn't mean the same thing as an active. It's just that the imperative of a deponent verb is going to be passive in form but active in meaning, just like virtually everything else about deponent verbs (participles aside).
I believe passive imperatives are pretty rare outside of deponent verbs, though. A passive command for an active verb can be rephrased such that the passive imperative is not needed. Besides, how often have you needed a passive imperative in English? "Be carried on his shoulders!" is more awkward than "Let him carry you on his shoulders!" ("Tē umerīs ferat"), isn't it?