I've uploaded an app yesterday (at 11 PM GMTT). I just looked at my uploaded apps and it appeared 3 times on the list. I'm pretty sure I only uploaded it once.
I've deleted 2 of them. The other is at https://apps.garmin.com/en-US/apps/48e25fa2-7ff9-4f11-8730-4c20a010b7bf.
(It's still awaiting approval, so the link might not work yet.)
I've had the same thing the day before, when a new app appeared twice on the list, but that might have been because of a crappy internet connection in the train, where I actually did try it more than once.