PA will catch this...
I agree with PAGUY...They will catch the OH DUI when they do the background check for ARD. This is an interesting case and a first that I am seeing. I think you would be eligible for ARD, but then lose your license for a year for an out of state DUI. The reason I say this is because I did something similar, but it was about 8 years apart. But for sake of argument, it could have been 8 days apart because of PA's 10 year lookback. I got a first in PA in 2000 and rec'd ARD. I got a second in NJ in 2008. It was treated as a second in PA and a first in NJ. It wasn't a true 2nd in PA, but they suspended my license for a year and req'd me to sign up for the interlocking device....I didnt have to do that because I chose to transfer my vehicle to a sibling and take public transit to work (1.5 miles).
Life is good right now. And any time I drink, I don't have to worry about hurting someone. I highly suggest people with 1+ DUI look into their local transit system. Go green, save green, save lives.