I would say that would be a bad idea. This is the kind of stuff that causes Apple to tighten security. By duplicating your values, you are basically risking Apple seeing that you're using one value for two machines. At best, they'll only block you, at worse, they write some algorithm that checks an additional value for all Mac users, making it even more difficult for everyone.
This is on of those tough issues. In the guide on the front page, even though the poster could have omitted the information, they chose to be transparent and include it. The problem is that some people don't have the patience to wait, and so they shrug, and proceed to use methods not recommended. When Apple catches on, and we all lose functionality, we risk the very real fact that we are left with no options.
I understand the desire to have a fully functioning Hackintosh. Hell, I just purchased a $100 network card so I could use iMessage, and any second now it will sign me out, and I'll have spent that money for two weeks of iMessage. Unfortunately, if we don't show a little restraint, we might find there are no options if Apple catches on.
So the answer I have to all your questions is this. Ask yourself whether the potential short term gains are worth the possibility of a long term loss. If you are only going to use Hackintosh computers for the short term, and will be purchasing legit Apple computers in the future, then go for it. However, if you are planning on making Hackintosh a part of your regular upgrade cycle, I highly recommend you not make any decisions that could potentially make that an impossibility.