It is possible to host a website on multiple domain name and redirect it to a particular web hosting account.
How can someone host a website on 2 or more web hosting account ?
It's kind of hard to get your question here... But i'll take a stab at it:
It's perfectly possible to use the same webroot for multiple virtual hosts... This means that multiple domains can point to the same webroot, hence serve the same content.
It's perfectly possible to have several a-records with different ip's for the same (sub)domain, in which case round-robin will be used
It's perfectly possible to move functionality to a subdomain on the same (or a different) host.
It's perfectly for most relational database vendors to do a master-slave setup, so even your relational database can be run from several hosts at the same time.
It's perfectly possible to return code 301 or 302 (temporarry or permanant redirect) to redirect your traffic to a different domain.
I hope the answer you search is in my post... If not: please elaborate your question