An improved sample of 31 double galaxies with accurate radio redshifts is defined and analyzed for the 72 km/sec discrete redshift interval effect. The effect is present at the 99.8% confidence level. Some doubles show significant deviations from the principal peaks and are consistent with a population of small peaks midway between (i.e., at 36 km/sec intervals). The width of the main peaks is slightly but not significantly larger than expected from observational error. Underlying natural width or structure in the main peaks cannot introduce a scatter much in excess of 6 km/sec. A sample of 30 new accurate optical redshift differentials shows the same periodicity.