The "location ID" tells them nothing about where the machine is. The only way they could tell that would be for the receiver to be connected to a phone line and for Bell to look at the caller-ID info. In general, if all of your receivers are connected to a phone line they won't bother you with the location ID calls. The receivers will call Bell TV periodically which will confirm to Bell that they're all in the same place (or at least using the same phone number).
As mentioned by others, the location ID is a number that changes in a fashion that is mathematically predictable, but known only to Bell. Having you read that number back to them supposedly confirms that you are physically situated in front of the receiver, which confirms that all of your receivers are in the same place since they make you do all receivers at the same time.
The cable companies complained about "cottage" service and the CRTC made the satellite companies stop allowing customers to have one account used for service at two locations. Their answer for handling "cottage" situations now is that you tell them which receivers are at home vs. the cottage, and only one set of receivers is active at a time.
In your case, if you only have two receivers active you should ask them to deactivate the other four. You can call and get them re-activated if/when you hook them up again in the future. You might be able to have them sit and wait while you do the ol' switcharoo with the receiver hookups, but it takes the receivers long enough to boot up that I wonder if they (and you) will want to wait through all of that.