VLAN database changes will not be sent to the other VTP domain.
I.e., if you add a new VLAN in Test VTP domain it will not be propagated into the Tets VTP domain switches.
Trunk negotiation also might not work if you connect two switches in different VTP domains.
You can use two VTP domains in your network (I was one year ago) if you need it for some special purposes, but you have to know exactly what you are doing.
But VTP protocol was designed by Cisco for one VTP domain in a L2 network and multiple domains are not recommended.
Regards,
Milan