This is under-documented so putting the good news that it is possible to open two graphs in individual windows at the same is indeed possible in the desktop version of Logseq:
- How to open a second window of Logseq
- Press the graph name at the top of the left-hand column (where it has a pointed-down triangle helpfully indicating that it is a drop-down)
- At the very bottom of the list of options, press “New window”
- Wait for that window to open and load the same graph that you are in (it’s as slow as a cold start) and now you can change the graph in that window, it will leave your first window’s graph alone.