Computer question

When I got my Probe inspected they told me it came up as a 4 cyl. I find that hard to believe but this is what I was told. Is it possible that the computer in my probe was replaced by a 4cyl computer and will a 4cyl computer work in a 6cyl. I have another computer from a 6cyl that I can change but wasn't sure if it's possible and that the 4 and 6 are interchangable. If they are is there a difference or are they they same?

Thanks
Maria