Whenever you load a factory preset , it loads into both A and B settings at the same time. Try selecting any UAD plugin in the master section. In the A settings, load any factory preset. Switch to setting B - load some other preset. The problem, is that when you set something up and want to try comparing it to the loaded factory preset, both settings A and B will be overwritten with loaded preset. Other plugins e.g. Fabfilter, Plugin Alliance do not cause this problem.
Are you loading from the WaveLab menu (load bank), or from a UAD preset menu?
The problem is only with the Wavelab preset menu (Load Bank). From the UAD preset menu it behaves correctly