Proper one-time encryption - like NordVPN uses - is already practically impossible to break, so immediately there is no security gain here with double encryption, but conversely it does not hurt either. NordVPN offers a special feature they call double VPN, where serial connections are made to two servers, whereby data is encrypted twice. This increases the credibility of the integrity of the encryption, as openness around the source code prevents 'dirt' from being introduced into the programs through the back door. It is recommended to use the Open as far as possibleVPN, WireGuard or IKEv2, as both are open source projects. In other words, there is great flexibility, which means that NordVPN can be used on virtually all units and for all purposes. NordVPNs software uses as standard the 256 bits OpenVPN or WireGuard encryption (however, IKEv2/IPSec in the iOS app, which is also very secure), but the other common protocols SSTP, PPTP, IPSec/L2TP and IKEv2/L2TP can be used as needed.
