To be honest, you're not providing quite enough information. The important thing here is whether the external IP addresses are doing incoming NAT for a web server that exists on the private network or if the web server is actually on the machine that has those external IP addresses.

I think my initial assumption was incorrect (that it was NATting the web server), but I added another possibility with an edit. Maybe you read my post before I finished the edit. Go back and see if it makes any sense to you: the unintentional and unneeded NAT of the internal machines to the web server addresses.