My neighbor had that and they call that a home run. They run a pair just for the modem and another pair (line) for your telephone. It can help.
Our IPC ran 2 telephone lines to our house to get 15 Mbps download and we are waiting on a new modem. I have never heard of using 2 telephone lines and can't find anything on the internet about it. Has anyone here heard of that? We were getting 10 Mbps before with only one. This has been going on since September. Supposedly we now have to wait until "corporate" approves a new modem.