Yes, it is feasible to have two BT routers operating within one house.
Yes, it is feasible to have two BT routers operating within one house.
The second phone connection won't function unless you pay the ISP fee.
Currently it seems they might be the exact same physical line. You can easily place two phones on one line (though only one call at a time is allowed, and you can talk on both phones during the same call). However, each line supports just one broadband connection.