That changes the mac address on that interface, for almost all practical purposes. If you set a custom mac address on an interface, the new mac will be used in preference to the BIA for everything except a few commands where you have the option to specify use of the BIA.
I can think of very few honest reasons for spoofing a mac address, though. What are you trying to accomplish?
Hello, we have the same problem. How to change MAC-address on int do0 while Do0 in root access-point mode? Command mac-address xxxx.xxxx.xxxx doesn't do any changes even with shut/no shut. After no shut "show int do0" show that bia mac-address is active.