Minimalistic LT3080-1 current source
According to the passage on p.10 of LT3080-1 datasheet,


  As shown in Figure 4, the two devices have internal ballast resistors,
  which at full output current gives better than 90 percent equalized
  sharing of the current.


This seems to imply that the tolerance of internal 25-mOhm ballast resistors is about +-5%.