The trick in my area is my ISP is a crown corporation that competes with the privately owned ISPs. They don’t give a crap what you do(as long as it’s not too illegal or damaging their service), the standard on their fiber is upload speeds are 1/2 the download speed and you can pay an extra $10/month for symmetrical. I put it to the test once as I was testing online backuo software. GDrive has a limit of 750 GB/day uploaded data, and I did that consistently for a couple months straight(IIRC that was pretty close to maxing my upstream at that time). Never heard a peep.
My understanding is this kind of thing is more common in birds that recently started laying. Combine that with the fact that birds tend to be kept with other birds of similar age and it’s not uncommon for a package of eggs to have either no double yolks, or multiple instances of double yolks. I’ve never seen a dozen eggs with just one double-yolk.