QUOTE(lotus_man @ Aug 10 2010, 12:22 AM)
but we're using d same account
Q: Can I use my iTunes account on multiple iPhone/iPod peripherals?
A: Yes, you can. As a matter of matter, both of my iTunes accounts are currently linked to my iPhone and iPod Touch. By linking them up, it means that you can now use a purchased content across these peripherals.
Q: Assuming that I intend to format/reinstall the operating system on my PC/MAC, do I need to backup the contents of my purchased contents (for example music, videos, movies et cetera) off the iTunes store?
A: Oh, yes. However, you will be pleased to know that, with Apps (from the App Store), you can actually re-download them again at no extra cost. This also implies that you can, technically re-download previously purchased Apps with your other iPhones/iPod Touch(s) (provided they carry your proposed and sychronised iTunes account).