Chance, alone, could not clump the universe as it apparently is clumped. It is obvious that the early universe was subject to great electromagnetic forces that shaped it before expansion moved things away. Things are too far away, now, for electromagnetism to have any effect. I think that it is likely that binary galaxies (such as our own Milkyway and sister galaxy Andromeda) were formed by some kind of beaming effect (like the poles of a rapidly spinning neutron star or black hole emitting matter). Gravity has little effect on small scale things, so it is not even considered in Quantum Mechanics. Charge and Centripital force dominate in the small world. Gravity dominates in the large world. However, during the birth of the universe, as patterns of mass were first forming, mass was close to powerful electromagnetic fields. Thus, it could have clumped mass in the early formation of the universe. That might explain why it is so very very common to see binary stars and binary galaxies (something like the Hall Effect in which opposite charges repel). Of course anti-mater tends to convert to regular matter. So, if one galaxy was made of matter, and the other antimatter, the two, now, would both be matter universes.