I think the question speaks for itself but here it goes:
I'm planning to use Backtrack to perform some security analysis on another linux distro.
Can I have both Backtrack and the other distro running as virtual machines in the same host machine.
Will the different VMs have an unique IP so that I can do stuff like pinging and such?
Yes, you can do this. Using a good VM manager, you can set up & configure a complete virtual network.
The simplest configuration that will allow you to do what you're asking is to create your 2 virtual machines, and configure their network adapters to work in "bridged mode". This will cause them to share the host's physical adapter, and will place them on the same subnet as the host.
If your network is configured for DHCP, the VMs should pick up addresses. Otherwise, you'll need to configure them manually.