CA (nee Computer Associates) announced in the fall of 2006 that it appointed Amy Fliegelman Olli and Kenneth Handel as co-GCs. The announcement is in Corp. Counsel, Nov. 2006 at 70. The joint position as chief legal officers has precedent at Citigroup and at Goldman Sachs. Both of those legal functions at one time recently had two general counsel. Perhaps one reason for the double heads is a fear of losing the one not selected? Perhaps this is the highest form of job sharing (See my post of Dec. 4, 2005 about job sharing.)?
I expect it is difficult for twin general counsel to sort out responsibilities and decision-making. Complex judgment calls are hard enough to make, and to expect two people who are equals to agree massively compounds the problem. To figure out who should make what decisions is impossible in advance, given the complexity of judgment calls that land on the general counsel’s desk.
Moreover, it is likely that some remnants of competition for the sole top lawyer position remain and the two lawyers may be aligned with different camps of executives. Beset with so difficulties it is for good reason that the practice is very uncommon.