Interesting issue when downloading BI SE1

When downloading BISE1 I faced an interesting problem. After some initial puzzlement I figured out it has something to do with IE (Internet Explorer).

There are two files you have to download for BISE1 from OTN:

1. http://download.oracle.com/otn/nt/ias/101321/biseone_windows_x86_101321_dvd.z01
   and
2. http://download.oracle.com/otn/nt/ias/101321/biseone_windows_x86_101321_dvd.zip
   

These two files have the same name, except for the extension. The first one is "z01" and the second "zip".


In Firefox, the file extensions are preserved the way they are, so that the two files are distinct when downloaded. No problem here - see the screenshot below.


But when trying to download it using IE, the extension is changed to .zip

IE for some reason decides that z01 should really map to zip, so that downloading both files results in one being overwritten.
So the solution, workaround, is to download them using the "Save As" option, manually specify the extensions to avoid this problem...

Wonder why this is happening why the way it is - this happened to me on two separate machines, and at least one other person from the field faced the same issue.