bindgen! fails when a world imports an interface both directly and under a label #14855

bindgen! fails to compile a world that imports an interface both directly and under a label:

world w {
  import store;
  import a: store;
}

error[E0428]: the name `store` is defined multiple times

It fails in either order, when the direct import is implicit through a use, and for realistic WASI worlds like include wasi:cli/imports@0.3.0; import a: wasi:cli/environment@0.3.0;. Worlds with only labelled imports compile fine. The WIT is valid (wit-component has an encoding test for this exact shape).

The labelled branch in crates/wit-bindgen/src/lib.rs (~518-535) generates the interface module at the interface's own path, and the plain branch doesn't check whether that already happened, so the module is generated twice.