@Kawz I found a solution to support multiple instances. This version of the bot does not close previous tabs:
https://catalog.botengine.org/FD575D579BC77305A45495B862F060206E93BC26F3ED39CEC87C5F05C74E4928
When you run a new instance of this bot with the same Windows user account, it opens a new tab in the existing browser window. If there is no browser window open by the bot so far, it launches a new browser window.