I have noticed in the last versions of the program that whenever I undo a duplicated node, as soon as I remove the selection of the item and re-select it, it returns two nodes in place, sometimes you even changing the node in place that happens.
This was an issue before... not sure if it was resolved. You might try searching the tracker: https://gitlab.com/inkscape/inkscape/-/issues
Beginners' Questions Duplicate nodes forever
Inkscape.org
I have noticed in the last versions of the program that whenever I undo a duplicated node, as soon as I remove the selection of the item and re-select it, it returns two nodes in place, sometimes you even changing the node in place that happens.
This was an issue before... not sure if it was resolved. You might try searching the tracker: https://gitlab.com/inkscape/inkscape/-/issues