Gravitational lensing turns out to be a source of double vision for Hubble.
From NASA (click here to get desktop sized versions from the source):
In this new Hubble image two objects are clearly visible, shining brightly. When they were first discovered in 1979, they were thought to be separate objects — however, astronomers soon realized that these twins are a little too identical! They are close together, lie at the same distance from us, and have surprisingly similar properties. The reason they are so similar is not some bizarre coincidence; they are in fact the same object.