 --> [ local path prefix ]/system/duplicate.fpp:3:1
  |
3 | system S2: T
  | ^^^^^^^^^^^^ duplicate system definition
  |
 ::: [ local path prefix ]/system/duplicate.fpp:2:1
  |
2 | system S1: T
  | ------------ previous definition is here
  |
  = note: each model may have at most one system definition

