Duo was two person video calls optimized for mobile phones, and allowing calling via phone number. Basically Facetime and Whatsapp. Again, a hugely popular product category that they did not have a product in, and with a paradigm that was not compatible with their existing video call app.
That's not to say these were good ideas, or that the projects were well executed. They were me-too copies of other companies' products, and possibly without enough understanding of what made those products popular. But the "duplicates" criticism is just lazy, and makes it seem that you're just parroting memes and did not know anything about the apps other than their names.
