This is a customer to customer forum not customer service but to answer your question BOGO offers require a new line of service. Verizon isn't going to give out $900 phones for free.
No. The Verizon BOGO offer requires that at least one of the phone purchases be on a new line.
You can however save just as much by purchasing the phones directly from Samsung with Verizon device payment agreements right now.
Samsung is offering an instant $310 off on a Note 8 purchased with a Verizon device payment agreement. You can get an additional $100 off by trading in your Note 5. So if you purchased 2 from Samsung and traded in both Note 5 phones you would save $820 without adding a new line or waiting on Verizon bill credits. The Verizon BOGO offer is capped at $799 and is applied in 24 monthly credits.