Multi OS Install Disk

I work for a university IT office and the computers that we see usually have
Windows XP Pro or Home.

I was wondering if it is legal to combine both version of XP onto one disc.
I know it is possible to combine then, as seen on the 8in1 disc, its possible
to fit up to 8 versions of windows onto one disc. We always use the user's
OEM license (sticker on computer) anyways, but it becomes a hassle when we
suddenly run out of XP Home or XP Pro discs.

Thank you.