Recently, a question arose about our RAID recovery software (www.freeraidrecovery.com), along the lines of "There is a RAID5 array, but I get some results if I try to recover RAID0 as well, what's wrong?"
Actually, there is nothing wrong. RAID Recovery requires the array type as outside input, along with the list of member disks. It has no way of determining if the provided array type is correct or not. Therefore, it tries to produce the closest possible layout for a given array type. There are certain cases (mostly involving RAID6) were nothing meaningful can be constructed, and it gives up with the appropriate error message. However, in most cases some layout will be produced.
If the original array type is not readily known and it is not possible to infer it from the number of disks and available capacity, the only solution is trial-and-error testing of all possible layouts (of which there are about four fundamentally different, RAID5/5E being practically equal).