Generally speaking if they've been separated from each other and you didn't notice any problems like was stated above for at least 3 months (I prefer to go for closer to 4 or 5, but it's a personal choice) then it should be fine. As long as they aren't in the same tub I see no problem, but again there are things that happen that we cannot foresee; there's always the small chance of your boa passing on a disease that she remained asymptomatic for, but again if you quarantined her for a decent amount of time before them being in the same rack then it should be just fine.