I think the impact is going to be pretty minimal. They're not even really advertising the 8pm timeslot, going so far as to advertise the "premiere" as being at 11:30.
I do wonder if this new episode before Toonami every week is going to dent ratings a bit?
I'm guessing it's part of the contract for Super that it has to air before a certain time so that kids can watch it. That's the only logical reason I can think of for airing the same episode that will be airing later on in the Toonami time slot.