TLDR: Don't even try scenario 1. It will damage one of your supplies and potentially overheat the strip. Fire hazard! Scenario 2 is safe but you will need common ground (i.e. common reference) for both supplies and your controller board
Long Explanation: Whenever there's doubt about something, always simplify your diagram. At the end of the day with know the logic just controls the LEDs and does not carry a whole lot of power (i.e. no safety concern). Your safety concern is in your power supplies
The problem lies on having your power supplies in parallel only separated by the strip. Ideal power supplies will put out a voltage independent of the current that the load demands. Therefore, it there's a mismatch in the voltage levels, one of the power supplies will be required to sink that current. As you may know, power supplies are good at sourcing current, but not sinking currents.
Lesson: Never, literally never, connect two supplies in parallel.
Scenario 1 - Left, Scenario 2 - Right
Image out of my own creation