Aeroad saddle clamp bolt stuck – J&L saddle clamp advice

I recently treated myself to a new Aeroad but I wanted to keep my old saddle which uses 7x10mm oval carbon rails. Per previous reddit advice, I ordered the matching saddle clamp from ebay.

However, this one came without the middle bolt and I cannot get the female part of the bolt off the original clamp that came with the bike. It seems fused to that side of the clamp. Can anyone confirm that this is the case or are you able to simply get the entire bolt out in order to use it with the other clamp?