There is no problem with having multiple Rokus (up to, I think, 20) linked to the same Roku user account. Each will independently be able to view any of the channel apps installed to the account that it wishes. Some of the channel apps themselves may limit how many concurrent streams they will support on the same channel account, but two should not be a problem.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
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Ultra 4800 | Streaming Stick 4K+ 3821 | TCL Roku TV 43S245/C107X