The rates are measured per hadronic Z0 decay for gluon splitting to bb¯ quark pairs, gbb¯, and of events containing two bb¯ quark pairs, g4b, using a sample of four-jet events selected from data collected with the OPAL detector. Events with an enhanced signal of gluon splitting to bb¯ quarks are selected if two of the jets are close in phase-space and contain detached secondary vertices. For the event sample containing two bb¯ quark pairs, three of the four jets are required to have a significantly detached secondary vertex. Information from the event topology is combined in a likelihood fit to extract the values of gbb¯ and g4b, namely
gbb = (3.07 ± 0.53(stat) ± 0.97(syst)) × 10−3,
g4b = (0.36 ± 0.17(stat) ± 0.27(syst)) × 10−3.