Thank you for your comments and feedback. You are right about the reset feature. There is at least one bug in that feature. I noticed the twin ship bug but didn't look in to it further. Also it would probably be a better idea to clear out the old asteroids when resetting.
The reason for including reset in the first place was to give control to the player when something goes wrong or when all asteroids cleared. There's a zone outside the camera view where the rocks and the ship can fly. The objects can sometimes get stuck in that zone and this is a problem especially if it's the ship that gets stuck; there's no way the player can get back in control. So instead of trying to figure out in code when the asteroids or the ship lose themselves in that zone I figured a better solution would be to give the power of control to the player.
The problem was that this feature was the last one I added. Time was running out and it was after 2 am anyway so I didn't test the feature properly but went to bed instead :)