Multiarchiteture with `dump` plugin how to?

Hi, I’m trying to build snap package for multiple architectures e.g. amd64 and arm64.

Below is my snapcraft.yaml and I’m building snap with: snapcraft --destructive-mode. As a result I’m getting two snap packages but both packages contain amd64 source. What am I doing wrong?

name: myapp
title: myapp
base: core22
architectures:
  - build-on: [amd64]
    build-for: [amd64]
  - build-on: [amd64]
    build-for: [arm64]

adopt-info: myapp
confinement: strict

apps:
  mybinary:
    command: bin/somebinary
parts:
  myapp-bin:
    plugin: dump
    source-type: local
    source:
      - on amd64: ./bin/amd64
      - on arm64: ./bin/arm64
    organize:
      mybinary: bin/somebinary
    stage:
      - bin/*