Jerry:
I was discussing this subject with a new client the other day ... whether he should have us build both courses, or find another designer to do his second.
The prevailing wisdom of marketing gurus is that two names are better than one, because it's all about the name to them. There are exceptions to this in modern development -- Devil's Pulpit and Paintbrush in Canada, all the Desert Mountain courses by Nicklaus, World Woods, and Stonewall, to name a few -- and all of them seem to have done all right. It is certainly understandable that a client would reward an architect who had performed well with a chance to repeat that success, but that is the exception these days, not the rule.
No one ever thinks back. Most of the best 36-hole complexes were built before marketing was king -- Royal Melbourne, Winged Foot, Sunningdale, Portrush, Baltusrol, The Berkshire, and Oak Hill, to name a few. It's hard to imagine those courses would fail to attract golfers today because they couldn't advertise Arnold Palmer's name alongside Gary Player's.