I get ultrasounds every week
I get an ultrasound every week and my baby is fine.
My husband knows a radiologist who did her own us 3 or 4 times a week during all her prengancy. She certainly thought they were safe.
Anyway, 2 us 15 days apart are completly safe, we all agree on that.
Some women have to get scans every week and their baby's are fine. 2 scans 15 days apart is not gonna harm the baby. A scan everyday on the other hand would probably not be a good idea.
Um... The safety is not exactly proven... I don't know why everyone thinks it is. There's a reason they only recommend a couple during pregnancy. Anyway, it's more about the length of time in one sitting that might make a difference, as well as the strength of the ultrasound (2d is safer than 3d). So getting 2 quick ultrasounds close together is probably safer than one really long one :)
Ultrasounds are never harmful. You could have one every day for 9 months, it would not do any harm ;)