They are probably feeding eachother. This doesnt have to be a sign of mating. Young birds feed eachother as well.
I would not seperate them. They are having a good time together and are very good friends if they are feeding. Seperating them would just cause stress and possible have them start screaming at eachother. If you just keep them in a cage with no nesting opportunity you shouldnt have any problems.
Are they boy and girl? Or two boys?
Kika: Senegal Parrot.
Guus: Cockatiel, Yellowcheek, cinnamon, pearl, pied.