creating multiple images in one packer build command

Question

I'm using the command packer build -only=*image1*,*image2*

I have few 'build.pkr.hcl' files with the following code:

build {

  source "source.azure-arm.windows" {
      name               = "image1-2016"
  }
  source "source.azure-arm.windows" {
      name               = "image1-2019"
  }

  source "source.azure-arm.windows" {
      name               = "image2-2016"
  }
  source "source.azure-arm.windows" {
      name               = "image2-2019"
  }

}

The issue is that only two images (image2-2016 & image2-2019) are built instead of four.

What do I miss?