At least one other site is using the same HTTPS binding warning when implementing IIS bindings for second application

when doing iis bindings for second application i got the following warning

At least one other site is using the same HTTPS binding warning when implementing IIS bindings for second application 

here what is the concept and how i do the HTTPS bindings for my second application

first application  created in port 443 , and has a hostname and ssl certificate 

https://www.fgh.com  

second application

https  site2.fgh.com has certificate site2.fgh.com