I have the same, though in my case it's because I had a different email address on my avios.com account (I didn't want to change it as it might mess up my Lloyds avios postings, but now I have little choice).

avios.com have told me that if I change the new BAEC account's email address to match that of my original BAEC account, BAEC will auto-merge them. And as I have now brought my avios.com email address into line there shouldn't be any problem with my Lloyds postings. We'll see!

Presumably if you correct your postal addresses the same should happen for you. (I can only look to change mine by calling, as I haven't got a PIN for the duplicate account yet). Best of luck.