If you opened a packaged game twice, it would open up the game twice on the platform you’re working off. However, when you say that you’re trying to open two instances of the same packed game, are you trying to test the networking capability? If so, you may want to submit a question to our AnswerHub for additional assistance.
When it comes to simulating games, the development and shipped version of the game are exactly the same, except for the fact that the development version includes the console commands. Therefore, if the simulation within the editor is exactly as you want it, it should package in debug, development or shipping exactly the way it looks. If you’ve noticed anything different, it’s possible that it’s a bug however, i’d need to know more information for that.
You may have already viewed this basic packaging documentation, but here is the link in case you haven’t: https://docs.unrealengine.com/latest/INT/Engine/Basics/Projects/Packaging/index.html