I'm aware that they pack multiple versions of firmware in same file (for example I used the "3.3" patch to update my SDS71021209xxx scope to firmware version 2.8.1.6), but that's not the answer here.
What I'm saying is that back when I downloaded the 3.2 patch, it had creation date of 2013-03-28 at 09:52 and size of 131.763.366 bytes. That file was downloaded back when 3.2 was the newest firmware. After that, 3.3 update appeared on the Owon site (and by Owon site, I mean owon.com.hk). I downloaded it (after some trouble, since they apparently never heard of character encoding on a HTML page, but that seems to be fixed now) and the file also had creation date of 2013-03-28 at 09:52 and size of 131.763.366 bytes. That looked strange to me, so I did MD5 hash of both files and got same result of ACBEBCF1B37A9B69DCDEE07EE6860837.
So that means that the 3.2 and 3.3 update files are completely same! Looking at the affected serial numbers, the only difference I can see is that the 3.2 patch has updates for SDS71021209xxx scopes, while 3.3 does not. For other scopes, it's the same. Publishing another 3.3 patch file gives impression to the users of non SDS71021209xxx scopes that there is in fact some change since the version 3.2, but in fact there is none, since they got the 3.3 in the first place.