I believe Bell still limits you to one 4K TV signal per household. You can watch other non-Bell 4K content like Netflix by streaming it directly on your second TV.
It is possible to watch live 4K TV with a second 4K box using the MediaRoom technology that Bell offers. Telus uses similar technology in western Canada and offers a second non-PVR 4k box to their customers.
I see you are posting from Bell Aliant territory. We have a separate Aliant forum, but the 4K technology and a lot of other things are similar since Bell took complete control of Aliant. You may want to use that forum in the future since there are still some differences in pricing, etc.