Unless that IP address belongs to a dedicated management network which implements additional security, it is a waste of resources.
Both IPs are, obviously, ending up on the same server. This means that, unless they come in through different networks (i.e. a management network that implements additional protection), there will be no difference locally between a connection to SSH going on one IP or the other: you can firewall these exactly in the same way (if you want) and it doesn't make any more or less obvious in the logs.
The only thing you're "hiding" is the relation between the SSH server and the web server and, unless you have very poor procedure for picking up account names, then it shouldn't matter.
If you're using a dedicated management network, however, it's a different matter: such a network could require all connections to go though a secure authentication phase and impose extra limitation on the conneting party (for instance, you can require them to be physically connected to the network, or go through a VPN requiring 2FA and making sure your client is "clean").