Both the Oscars will clean the rock and excavate her substrate.
The next time the female start laying eggs, have a look under what you think is the Male, he should have a small spike sticking out of him.
I have got to Green Severums that I have since found out are 2 females. Green Severums breed exactly the same as Oscars. Thing is, they behave like a breeding pair. Both of them clean the surface of what ever they are going to lay eggs on, they chase each other around. When they lay eggs, they are both around the area and one of them even swims across the top of the eggs after they have been laid. However, I have twice seen both of them laying eggs so I know there is no male. Oscars will do this as well.