Hi Ben, welcome to the forum.
It is nice, particularly more recently, that the community has picked up from purely H/W analysis, to S/W enhancements too, Linux versions etc.
A good question, no I don't think it has been asked specifically before. Yes, a simple continuity test between the probe ground clips (or the ground tab adjacent to the cal output) and the USB connector (shell and ground contact) will be sufficient to confirm that it is an Isolated version. If you want a bit more certainty, you could add a few more volts, say, a 9V battery in series, but as the idea of the galvanic isolation is to break ground loops, rather than the dodgy practice of floating the scope at high voltages, there is no need to worry. The isolation components are rated for several hundred volts, so there's no risk involved in a simple continuity test.
As far as I can tell, they VDS1022 hasn't been "cloned" as such. There is a PeakTek re-brand that came up a few pages back, but it's the same H/W from the same OEM (still Owon AAFIK).
Chris.