Andrew Aitken and Greg Olsen, founder and senior partner of Olliance respectively, will join Black Duck after selling the company.

Black Duck Software, a US-based provider of software compliance management services backed by Germany’s SAP, has made its fourth acquisition by buying consultants Olliance Group for an undisclosed amount.

Andrew Aitken and Greg Olsen, founder and senior partner of Olliance respectively, will join Black Duck after the two companies formed a partnership with each other in March. Previously, Black Duck bought Koders.com, Ohloh.net and SpikeSource, with the final two coming in the last quarter of 2010.

Tim Yeaton, executive…