Windows 10 Pro supports up to 2 remote desktop sessions
Here is how to enable Windows 10 for two Remote Desktop Sessions
open Regedit
Apply this key
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Terminal Server
REG_DWORD “fSingleSessionPerUser” value 0
A value of 0 allows 2 sessions. A value of 1 allows 1 session