They probably are just sizing each other up until one kills the other off. 2 Oscars need about a 150 gallon tank to MAYBE live in peace, most of the time they still kill each other off. If you do have a male and female they may pair up and breed once they get to about 6 inch's for the female and 8 -9 inch's for the male. I takes about a year to a year and a half for they to reach sexual maturity. But most likely you got 2 males and they will kill each other off, it always happens. It could take years and it could take days but given a long enough time line in the same tank they will kill each other.