I don't think that there is a technical reason for requiring a new access card when a receiver is transferred from one customer to another. I do it all the time with commercial properties, though they won't reauthorize older non-mpeg4 receivers.
The reason they may require a new card is...
For the sanctimonious snobs(to borrow a phrase): ....the description at the top of this forum says "for those having trouble with their Directv equipment...
Well, as a matter of fact I am having trouble since the HD guide software update. The modulated SD output doesn't work as before...
Check your receiver setup and make sure that it is set to match your dish. If you are trying to access a satellite that your dish won't receive it may cause a problem.
Here's what is says on the guide:
The N, the network for teens, is the home of hit shows like Degrassi,
South of Nowhere, Instant Star, and Beyond the Break.
The N's mission---to be authentic and entertaining---is carried out seven days
a week.