(d)where a person subject to naval law, whilst a sentence on him is so suspended, is sentenced to imprisonment or detention for any other offence then, if he is at any time committed either under the suspended sentence or under any such subsequent sentence, and whether or not any such subsequent sentence has also been suspended, the committing authority may direct that the two sentences shall run either concurrently or consecutively, so, however, as not to cause a person to undergo detention for a period exceeding the aggregate of two consecutive years.