Does dual military living in base housing receive one OHA and the other doesn’t?

OHA Payments to dual military couples will not exceed the rental cost. Dual Military are each eligible to claim OHA, and if you have dependents, then one member can get the dependent rate, but the not to exceed rule still applies. If you are eligible for up to $1000 a month, and your spouse is eligible for $1000 a month, you could rent a place for up to $2000 and get reimbursed. If you rented a place for $1400, one member could get $1000 and the other would get $400 (or $700/$700, the split doesn't matter).
Since you are in base housing, I assume you are not paying any rent, or if you are, the amount is less than the OHA cap for one member. If not, you should have a claim.

DOD 7000.14-R, VOLUME 7A, CHAPTER 26