I can book the following trip:
12/21 AA129 SJC-NRT 11:55-16:20
12/22 JL711 NRT-SIN 17:50-12:55(+1 day)

But I cannot book this trip:
12/21 AA129 SJC-NRT 11:55-16:20
12/22 AA5836 NRT-SIN 17:50-12:55(+1 day) -- AA codeshare operated by JAL, same plane as above

Is there some sort of minimum connection time between AA-AA international codeshares which is different than AA-JL connections? The connection time is 90 minutes and both versions of this trip are on the same plane. I'd rather fly the AA codeshare to get a 100% mileage accrual as opposed to the 70% I would get on a JAL flight.