We did this in 2008 (except it was April and November). Never regretted it!
We almost didn't do it because I thought I wouldn't enjoy the 2nd trip as much, but I did! However, we went by ourselves in April and with family in November so I suppose that may have made a difference. They were very different trips.
I remember not being as excited (or even looking forward to) the November trip. I may have cancelled it if we weren't committed to going with other people. I'm just that way, though. I always come back from a trip thinking "That was great, but we can skip it next year and go back every other year." Here I am, trying to squeeze in a trip this year even though we just went less than 5 months ago!
So, GO! And if you come back and think you don't want to go back so soon, don't worry, it will still be fun....JUST GO! I also agree that you should go as much as you can while it's "cheap". We have one Disney adult and it has gotten much more expensive. Having 2 may make us skip WDW for awhile - unless there is still free dining - but that's a whole other thread!!