After a few tests to confirm, mostly what I had experienced previously: If you upload a file to Lr Web first, then try to Import the same file into synced LR Desktop, it will not (if 'Don't Import Suspected Duplicates' is ticked) as the Original has already been synced back to the Desktop. If you Import a file into Lr Desktop first, share a Collection (with that file in, which will only then be a Smart Preview) to Lr Mobile, then try to upload the original to Lr Web, it will not, as it's considered a duplicate. Both which are expected (although a bit of a shame you can't overwrite the Smart Preview in the Cloud/Lr Web with the Original). I haven't tried to upload to both platforms, then turn sync on. I imagine some conflict will occur. Will test on my unused work account and see what happens.
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