Yes, for accounts created with Rithmic data—specifically where R/Trader Pro was selected as the platform during purchase—it is possible to be connected to two platforms simultaneously.
To do this, simply follow the guide here.
Also, for accounts created with Tradovate data—specifically where either Tradovate or NinjaTrader was selected as the platform during purchase—it is possible to be connected to two platforms simultaneously. You can be logged into both NinjaTrader and Tradovate at the same time.
However, when using TradingView, you can only be connected through Tradovate, not NinjaTrader. This limitation is due to how TradingView manages broker connections.