Русско-англо-русский юридический словарь

Concurrent sentences. Concurrent terms of imprisonment are served at the same time. For example, if a person is sentenced to six months imprisonment for one offence and six months imprisonment for another offence, the total effective sentence (that is, the time they will actually spend in prison) is six months. (Go To Court Lawyers)

Merger of sentences occurs when a defendant is convicted of two crimes that are indistinguishable from each other, for which he should only serve concurrent sentences. (Wyoming Law Review)