Druid distinguish OPEN_FILE command callers

I'm following this official example to open a file via a dialog box. In my case I have two buttons to open different files and I cannot distinguish the caller of the command OPEN_FILE to perform different actions. What is the correct way to handle the problem?

This is a companion discussion topic for the original entry at https://stackoverflow.com/questions/73385761/druid-distinguish-open-file-command-callers