Create a project with the following minimal setup:

.
├── dune
├── dune-project
├── liba
│   ├── dep.ml
│   ├── dune
│   └── liba.ml
├── libb
│   ├── dep.ml
│   ├── dune
│   └── libb.ml
└── mytest.ml

Both dep.ml files should look like this:

let x = ()

Both liba.ml and libb.ml should look like this:

module Dep = Dep

mytest.ml should look like this:

let _ = Liba.Dep.x
let _ = Libb.Dep.x

If you try to jump to definition on the "Dep" or "x" of the first line, you will be brought to libb instead of liba. However, if you change the implementations of the two dep.ml files, e.g., by making the one in liba assign "a" to x and the one in libb assign "b" to x, the jump to definition works properly.