As far as I've been able to tell, the attack speed is exactly the same... If you are willing to post your numbers here that will probably help your case, but I honestly doubt there is any difference since an extremely small difference can be easily caused by human error. It also seems you're implying the bars don't lie too badly, but they clearly do. The GF's bar implies that it's twice as fast as the DA, when it clearly is not, even if a slight difference exists as you stated :P
This is probably a given, but be sure you tested both weapons with the same exact gear/UV's so that the final ASI bonus (if any) will be equivalent when testing each sword.
Anyways, I'd like to see those numbers :3