I forgot.. Census Day
But a question popping up. Why are you getting a 2nd form if you already sent in your form? Basically for lots of areas its easier and cheaper to mass mail a 2nd form to everyone than to sort out who did or who didn't send them in. and there are printing issues that would prevent spot printing on demand at this scale.. All these forms were probably printed years ago.
Gotta give the marketing folks at the Census Bureau some credit. Lots of play with their map showing response rates. Realize that a lot of areas and neighborhoods really can't rank high in terms of their response rates. Everywhere the Census could identify a mailing address gets a form and in places where there is concentrated housing vacancy there can't be anyone to respond. That will show up as a low response rate. Just the way it is. In fact I suspect the final results will be mostly a proxy for vacancy, but we will see.
That and if you are confused why some areas are not showing up on the map.. long answer, but it's an artifact of how the Census Bureau accounts for local municipalities in Pennsylvania. they wind up itemizing data for boroughs and not townships..