Hi,
Is there any harm in using the same worker for multiple machines? I have a bunch of slow machines that I planned to use, but I didn't want to have to set a worker for each of them. I realise that it will make troubleshooting individual machines harder, but are there any other issues?
You can connect as many miners as you please using the credentials of a single worker. It causes no harm.
What you may notice is that your miners will find fewer shares, because the share difficulty will adapt to your hashrate. However, this will not affect your earnings, as higher-difficulty shares are worth more.