Can I sync calendars and contacts from two mac accounts with one iCloud account?
You could have two iCloud accounts and sync both calendars to your iPhone.
You can achieve the same result if one or both of your accounts is on Yahoo, Gmail or Exchange, without the need to create two iCloud accounts.
If having two calendars that you can switch on and off is your concern, you can have one iCloud account, under one user account in your computer, and two calendars, named "Fun" and "Work", and reduce the hassle.