[dnanian]

Yes: the disk format is the same for all three, it should be no problem.

Note, though, that if this drive is going to be physically connected to one of the Macs, I'd create a partition for that Mac so you can do a direct backup, and then a partition for the other two sparse images. Make sure the partition format is appropriate for the Mac type (if this is an Intel Mac, I'd use GUID, otherwise Apple Partition Map).

Hope that helps.