I looked this up and Massachusetts is actually extremely strange that they count "last months rent" separate from "security deposit." In my state any money required to be collected past the first month's rent is legally considered a security deposit and required to be treated as one and subject to legal limits on security deposits. Which makes sense.

It's logical not to bother with the requirements of an extra security deposit if you can go ahead and collect two months rent up front without calling the extra a deposit. In my state the standard is also to collect two months rent up front - because the standard security deposit is a month's rent.