After really do a whole bunch of research on this (believe me!), I've come to the conclusion that my hunch that the "three headed frog" is actually three separate frogs is correct. First, the article says that the little kids lost their frog(s). Evidently, after much searching, the frog(s) cannot be found. No scientist actually examined the frog(s), either. There were just a few still pictures taken of the frog(s).
It is much more highly probable that these are three separate frogs -- a female on the bottom with two males holding onto her, side by side. This, actually, is not unusual and happens very often. In my studies of amphibians, I have actually had male frogs grab my hand and hang on like that (They sure liked my hand!). You'd be amazed at how tightly they will grip you! In the wild they will hold onto the female and tightly grip her until she lays her eggs in the water. It is at that time that the male(s) fertilize(s) her eggs. Toads do this, as well.
To the casual observer, it certainly would look like like these frogs were some sort of Siammese triplet-freak. In fact, to remove those males, if they were, indeed, in the midst of mating, would be a difficult task because their hold is so tight and can go on for several hours.
So . . . forget the notion that these are Siamese triplets! They're not even conjoined in the way they would be if they really were a freak of nature.