The ISS Enterprise (NCC-1701) was a ship in the Mirror Universe that is almost the same in design and decoration to the USS Enterprise in the "normal" universe. It also had some connection with the real Enterprise allowing the crews to crossover with each other during an ion storm. This connection was shown in 2267 when crews from the two ships crossed over.
It also mirrored the design of the Constitution-class Enterprise. But was distinguishable because of the constant appearance of a dagger through Earth (symbol of the Terran Empire).