When creating an os+db image, Packer throws an error: Error updating template: ide1 - cloud-init drive is already attached at 'ide0'.

The reason is that Packer did not remove the old cloud-init and trying to insert a new one.

The removal occurs in the code: https://github.com/hashicorp/packer-plugin-proxmox/blob/main/builder/proxmox/common/step_remove_cloud_init_drive.go#L56

If you create cloud-init on local disks, the file name will also include the disk format:

 my $scfg = PVE::Storage::storage_config($storecfg, $storeid);
        my $name = "vm-$vmid-cloudinit";

        my $fmt = undef;
        if ($scfg->{path}) {
            $fmt = $disk->{format} // "qcow2";
            $name .= ".$fmt";
        } else {
            $fmt = $disk->{format} // "raw";
        }