Ya you can host files off it and everything but you cant have the same domain point to two different machines with out some equipmnt inbetween to do loadbalacning or having the machines connected via a VPN in such a way that if one goes down the other gets all the traffic.
Each physical account would have to have its own domain or be a subdomain of the main domain. Like you could do your website on one account at
www.mydomain.com and host files at files.mydomain.com where the second domain is a subdomain of your main domain and thats where all your files are stored and linked.
If www. goes down people can still get your files (if they know the path) and if files. goes down then they can still see your website but just not get any of the files.