Time will tell if it is aggression or mating ritual.
Discus of the same sze rarely hurt eachother. It is normal cichlid behaviour to be a bit territorial. t's quite interesting to watch.
Many cichlids get a bit destructive before mating.
Angels for example, nip at plants.
time to try the following
lights off
temp to 32 celsius
crushed garlic mixed with frozen bloodworms and flagyl at every feed
25% water change every two days
clean out any uneaten food, but give discus a couple of hours to try to eat.
do this for two weeks.