Re: Double Grading!
well... it all comes down to the way you instructor decides to interpret the rules of the given association.
In Denmark we have a standard curriculum for 5th. kyu to 3. dan. Each dojo can decide if they want to have a 6th kyu grading. In my dojo we do. It has the benefit of being a very easy way to get your feet wet when it comes to gradings. It is very basic stuff and requirements are not that big. 15-20 training days will get you there. What does happen is that some get a minor revelation and realize that grading is not bad, and that it help you to understand better what you have actually picked up so far.
I have on one occasion jumped one person from no-kyu to 5th kyu. He had participated in a week-long seminar with 28 hours of training in six days. So he was way ahead of 6th. kyu. I would maybe do it again in a similar situation or for somebody who had extensive experience from a different type of aikido or budo... but I expect that's it. Don't think I will ever let somebody jump any ranks above 6th. They will be better of putting the hours in.
Anywho. Congrats on the grading - now go practice. It's the only thing that really matter.