Can we use same IP address for Virtual server and Same IP on SNAT pool?

Yes, you can. SNATPOOL is used for egress traffic, so here it will be your VS address going as outbound traffic.

You can read through the doc's for more understanding. It all depends on the infra and how one would like to use it. Some use self-ip's, some use a pool of ip's & some prefer the same VS address as the snat address.