Define what the second window must do
Two VLC windows can be useful when comparing an original clip with a revised owned edit. Decide whether you need two independent playback sessions or simply another item in the same playlist. Record the installed Windows and VLC versions and preserve the current preference values before changing launch behaviour.
Choose short authorised sample files with clearly different names. Set a practical comparison arrangement: window labels or titles visible, one audible source at a time and an obvious route to stop each session. Opening two videos does not itself create synchronised comparison, and this guide does not claim frame locking or hardware capacity for concurrent playback.
Review both instance preferences
In Tools > Preferences > Interface, the desktop 3.0 Windows guide identifies Allow only one instance and Use only one instance when started from file manager. Disable both for the documented independent-instance workflow. Review both when the intended task includes double-clicking media files. A setting that allows a manually launched second application may still leave file-manager opens directed to an existing instance.
Apply the documented change in the Interface preferences and save it. Match the labels to the installed build. Do not copy the guide's separate macOS workaround into a Windows plan or imply that Windows instance controls establish native multi-window behaviour on every VLC platform.
Rehearse the two launch routes separately
First launch the application through the intended normal route and open the sample. Then exercise the second route you actually use, such as opening another file from the file manager. Inspect whether the second file enters a new session or the existing playlist. Record each outcome separately rather than writing two windows work after checking only one route.
If the result is unexpected, inspect the two instance values and the actual launch method before reinstalling VLC. A file association, shortcut or old running process can add context that should be recorded locally rather than assumed away. No Windows installation was changed or tested for this guide, so these are acceptance steps for the real setup.
Keep the comparison interpretable
With the intended windows present, make sure the user can identify which edit is being viewed and which window has keyboard focus. Mute or pause the other session during audio review. Two simultaneous soundtracks can sound like an echo or mix problem in the media when the actual cause is two active players.
When the review ends, stop both sessions and decide whether to retain the changed preference. Keep the previous values if ordinary viewing should return to one instance. The successful outcome is predictable independent launching for the named Windows workflow, with no claim of automatic synchronisation, universal performance or identical behaviour across operating systems.
Questions answered
Why check the file-manager preference separately?
The documented Windows controls distinguish general single-instance behaviour from files opened through the file manager.
Do two VLC windows provide synchronised A/B playback?
Do not assume so. This guide concerns independent instances, not frame-locked comparison.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.