Very true, learned-from-experience type advice. Some banks my not really get the need and ask a bunch of questions, but in my experience they were more excited for the opportunity to charge more credit card fees :)
I would suggest to get the second business card (not for every employee, but for paying your critical service bills) from a different provider altogether, since the goal is to make sure the backup works when the primary one doesn't for whatever reason. So choose for example your bank's card as primary, with a corporate Amex as backup.