So the input output linking "wire" is drawn on the javascript canvas with ctx methods/commands.
Possibly with nodeeditor modifications.
Google search of (ctx canvas javascript) brings up explanations and examples.
For example: https://www.w3docs.com/learn-javascript/canvas.html.
So drawing the second wire should be relatively easy.
Duplicate some code, and adjust the y values for "startpoint". "endpoint" may be the same y "offset".
- Brian