As the circle radius increases so does the length of the curve. So these points that you have selected on each curve are in fact the same distance from t=0 around the curve. The quick solution is to reparamaterize the curve input at C of the Eval component. Or alternatively use the Eval Length component.
Reparameterize your circles. (Right click the C input of the evaluate comp. and choose reparameterize. NB: random then needs to be in the range from 0 To 1)