@Mauro ********
in the old days, the visa was a sticker in your passport. Immigration was NEVER allowed to transfer this sticker, they didn't even have any supply of these stickers! The sticker were issued by the Thai Embassies abroad. You entered with both passports and received you entry stamp into the new passport. In case you were already on a "1-year extension of stay", this was (and still is!) a stamp from Immigration, and this is the only thing Immigration is allowed to duplicate (transfer) into your new passort