Vintage T-Shirt Forum & Community Authentication Appraisals

Hello...
I would like to refer from the old timer, regarding the Register Number on Vintage Nike Blue Tag t-shirt...
As we all know, the Register Number for Nike brand (t-shirt) is RN56323...
Since Thailand already start producing fake vintage nike tees, now we are wondering what if we found a Vintage Nike Blue Tag t-shirt at any flea market, and behind of the tag there is no Register Number?? You can see the example from the attached picture.

So now, my question is:

1) How is the best way to recognize between the original @ the fake one?

2) If behind of the tag have no Register Number, is it original?

3) How bout Nike orange tag, is it also have the Register Number?

Note: This is really important for us, because Vintage Nike stuff is really a WANTED item in Malaysia market...So we want to prevent from being cheated by asking from you guys, the expert & the old timer...Thanx!!

Honestly, alot of these fakes are just too good. I visited a customer's warehouse a week ago and he had piles of everything from Maiden to Harley, all with legitimate looking tags to match. These guys photocopy the original tags, pay attention to the print, the stitching on the shirt, etc. There are obviously mistakes but the real serious guys do a good job of cleaning up their stock.