" They both uses the same ip and same port(80)."
They do not. It is a DNS problem.
pinoybpo.com. 68.180.151.74
healthcaresupportstrategies.com. 98.136.92.79
When it resolves the hosts name to the IP address it resolves to completely different numbers.
I presume that pinoybpo.com. 68.180.151.74 is correct so get healthcaresupportstrategies.com.to point to that IP.
At the moment it is not getting to your server. There most be some other redirection on healthcaresupportstrategies.com. You want to control this.
Contact the people that hold your domain registration to fix this.
At the moment it is not an IIS isue.