2 spaces work like 1 spacebar, but is just more comfortable. I mean that it works only when u press it, so? It's still about your timing. for more it doesn't work when u incidentally press 2 spaces at once, it just blocks u.
Well ppl using 2 spaces have often faster tap than twichers. I don't say about ppl like Mablak, who has been playing for 10 years + he put some stuff under his space. For more fr isn't easy, so mostly ppl who use it don't get so fast tap at start, or just can't control it. Just take a look on Anubis, well I have never played with him, just heard that he had got fast tap and he used fr.
People can fr all they want, it doesn't make them win games. However I think its absolutely retarded for anyone who fr's to get any credit for tapping fast. If you have such fast fingers, use 1 space. Obviously you cant tap fast enough so you have to resort to fr.
Example:
1 space is tapping at 1 mph
2 space is tapping at 1 mph
The person using 2 spaces is actually only tapping at a speed of 0.5 mph.
No matter how fast you are tapping you will always be actually 50% slower.