Nagvis & multiple instances?

I am using Nagios 3.0.6 with NagVis 1.4rc1. I have 2 different Nagios-instances on 2 different machines that monitor multiple servers. On both servers runs NDOMOD, both NDOMOD-instances report to the same MySQL database. Nagvis uses this database, but I can only configure Nagvis to use data from 1 instance (dbinstancename).
I would like to make graphs with data from both instances, but can’t make it work. This seems strange to me, one of the features of NDOUtils is that you can report from multiple instances to 1 database, so why can’t NagVis make use of the data of all instances?