I can't say for sure without tasting it myself, but, I doubt it would be fair to enter as a regular dubbel -- you've significantly fruited the beer, which might put your beer at an unfair advantage, or even a disadvantage if it tastes TOO fruity. I would enter it as a 16E Belgian specialty, and let the judges know what you all put in there, assuming you can taste it, of course. If you can't taste a particular ingredient, then don't even mention it to them. I've done this before where I had a spiced Biere de Garde with vanilla, nutmeg, and black pepper. But all you could really taste was the nutmeg, so that's all I mentioned to them. Sure enough, the judges found all sorts of nutmeg flavor but no one mentioned anything about vanilla or spiciness. This is really key -- tell them what it tastes like so that you'll meet their expectations. And if none of the fruit is quite obvious enough, then yeah, go ahead and enter as a regular dubbel. But assuming it is tasting fruited, then you really should enter as 16E Belgian specialty.