1- Can two separate NICs be installed in one PC and have separate IPs
Yes. There is nothing special about multiple NICs in one system. I suspect it is even standard on allmost all servers, and both desktops setting next to me also have dual NICs (and soon a third, a pair of 10GBit NICs have been ordered).
The term for a computer with multiple NICs/IPs is "Multihomed"
2- Does this seem like a sensible approach to generate/check the data
transferred over this interface?
No, dor several reasons.
- ICMP echo request (aka ping) is not a good test. Try to use something like iperf.
- Routing can get tricky. As can CPU usage. Best to split that cleanly into two systems.
- And, as Alex already mentioned. Sometimes the OS tries to be very smart. It is easier and more foolproof to test with two different computers.