There's no way to synchronize the outputs of multiple Roku devices. I don't know if any streaming devices from any manufacturer have that capability. If you want the video to be synchronized you only need one Roku device connected to an HDMI splitter and a bunch of high quality HDMI cables if these TVs are separated by any significant distance. I've seen HDMI splitters with up to 16 outputs for around $100, but I don't have any experience with them.
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