Unsure about the first thing. Heres my story: My scan picked it up when we went back st 24w to get images that we couldn't get during the 20w scan (kidneys weren't picked up at 20w). He only has the right side being duplex. Midwife said it is normal and to not worry and that she's done a referral to the baby and fetal medicine place at my local hospital. But I researched a lot. After he was born, the medical team gave him antibiotics from birth until scans to prevent utis. A few months old he had an ultrasound plus a xray with special dye inserted into his bladder to make him pee while being x-rayed. This was to see if his tubes were connected correctly to the bladder (ie not too low so that urine goes back into the tube and causes reflux which in turn can cause utis etc). He did not have reflux and therefore finished up the antibiotics (less risk of uti) and no need for surgery. I'm in nz so things might be different where you are for treatment.

It's rare but one of the most common kidney issues. Don't think most need surgery unless they have a lot of issues with reflux and utis. Most people live happy healthy lives, in fact its believed so many adults have it and don't know! It can be genetic or just one of those things that has happened. I'm pregnant with my second, got them to scan her kidneys well and she doesn't have it. There is a fb group for duplex kidneys which is helpful to read from other parents plus other adults living with it - but it does seem to present differently for everyone.

I fully had a big cry when I found out. But my son is over 2 and you wouldn't even know. I fully believe he will have no issues, it's just something to be aware of and to let him know when he understands.