Just once, but keep in mind all my boxes were calling in from the same phone line for years, so they probably knew I was legit and NOT account stacking. I still had the ViP's for years after that with no further audits, but I think it confirms that Dish WILL audit even if all lokes legit on your end. Remember, it is the high number of boxes they are interested in confirming, not so much a 2 box account.
Keep in mind that once the you and the auditor are connected (by telephone), if for ANY reason the connection is lost, such as low battery on your wireless phone or ANY reason, even before the audit begins, YOU WILL BE SHUT DOWN (they go through a scripted introduction and explanation of what they expect and they will do such as shutting down your account immediately during the phone call if they feel so compelled), and have to call and resolve this with Dish, so they aren't tolerating anything at that point, but that can be a pain if someone is legit. During the audit process, you will be given only what seems a "reasonable" amount of time to go to each TV and read the numbers because they are aware you may be putting in a call to the other household about being audited.
In short, Charlie would rather SHUT YOU DOWN and take whatever complaints and even LOSE you as a customer than allow the loss due to account stacking. Auditing will always err on the side that you are account stacking and shut down your service requiring you to address whatever issue and re authorize service. Of course, Dish will always be more than happy to immediately re-authorize all the boxes in all the locations--as separate accounts. No hard feelings and a new LOVE because Dish will be getting all the hard cash it is entitled to under the Residential Agreement. "Have a good day, and thank you for calling Dish."
There are a lot of gray areas in life and even in satellite, but account stacking is really over the line and just plain theft. I shed no tears for account stackers who get shut down. If someone wants remote viewing, I recommend a Hopper with Sling or a Slingbox.