If you are only using service at one location at a time, there are two ways of doing this without needing a second account. First, if you use your vacation home for long periods (for example if you are there all summer) DirecTV will allow you to move your service address between your regular home and your vacation home and you will need to have a dish installed at your vacation home (or install it yourself) - then just take the receiver(s) with you when you move to your vacation home. The second way to do this, if you are at your vacation home for short periods, is to install a dish at the vacation home and then just take your receiver with you. Although this is technically in breach of the DirecTV terms of service, many people do this (for tailgating at football games for example) and DirecTV does not seem to consider it a major problem.
One thing you need to consider is your local channels. If your vacation home is some distance from "home", and you just take your receiver with you without changing the service address, you may lose all local channels because you are out of the spotbeam that delivers your locals. 100 miles is usually safe, 200 miles can be OK for SD locals sometimes but often you won't get "your" HD locals. If you move your service address, you will get whatever local channels are associated with the vacation home location. If you want to keep a Rec at your vacation home order one as a RV Use and leave it there.