Not quite sure if I'm misunderstanding what you're trying to determine.
Do both of the DNS CNAMEs point to the same MX? I would think that you would be pointing to a different MX depending on which VPN hostname they connected to. In which case the clients would be listed in two separate networks. vpn1 will be for MX1 in network 1. vpn2 will be for MX2 in network 2. Each site will have its own client VPN subnet that is being used to hand out IP addresses. You could deduce which VPN they are connected to by looking at the IP address that the client received from the MX.
Even if you're using a DNS load balancer to spread out the clients, you would only see the client connecting on the network that they ultimately get routed to. However, in this case, you wouldn't really be able to rely on any of the historical numbers as users could easily be hopping from one to another.
https://documentation.meraki.com/MX/Client_VPN/Client_VPN_Load_Sharing