I think the guy seerat met is not Garry. If it was Garry, her reaction would have been so totally different, u know seeing your dead husband alive type expression . He is probably the Scam guy. I think Scam guy has some old relation with serat. He will probably blackmail Seerat to tell him all the details about Angad, like how to make people belive fake Angad is real Angad and then steal the Diamond and make Real Angad be fake Sunny. For that they need elaborate details about Angad's life and they uses Seerat for it.They will make everyone belive fake person is real Angad. The watch Sahiba bought and her name for him(Gabru Sardar) might be the one that will set the real and fake Angad apart. Only Sahiba will recognise Real Angad( she might not be able to gift the watch to Angad, and fake Angad will say Sahiba gave him the new name, which everyone in the house already knows and they will belive fake one is real one bt only Sahiba will know... something like that)
PS. Just some my theories..