Yes, this is at least a second such collision recently.
Water flying introduces variables, which are uncommon in wheel flying. Few bodies of water are "aerodromes", and thus have established traffic patterns. And, the landing zone will be that which the pilot chooses, based upon their preference and experience. So, two floatplanes, particularly two who's pilots are unaware of the presence of the other, could be set up for very different approaches. High wing planes of course reduce visibility in turns. This has been ridiculously aggravated for some Beavers, which were former US Army. Those planes, very wisely, had four excellent skylights, making it much easier to see traffic. When converted to civil, it was a requirement to cover them over, I can't imagine why!?! If I were making the design requirements, I would require skylights, certainly not close them over!
Float flying gives you that wonderful sense of being on your own, out in the wild. That feeling of freedom can reduce one's vigilance for other traffic...