I don't know if you have to upgrade your magnet radius all the way, but if you open the menu with coins on the ground, then you can pick them up while still in the menu. >.>
I am not quite sure how I did it, but after completing abandoned house I went immediately to the "stuff" tab and equipped the reward.Then, I pressed the left arrow key, and it gave me the reward again!Only worked once though.
 "Enigmata: Stellar War"){kind=icon}
 "Villainous"){kind=icon}
 "IncrediBots 2"){kind=icon}
 "Chuck the Sheep"){kind=icon}
 "My Pet Protector 3"){kind=icon}