Thanks... but unfortunately I just discovered some additional bugs. Crate contents and jar contents don't appear to reproduce reliably with a custom seed, even though level layouts, shop contents, and so on do reproduce. There is some stuff going on I don't quite understand. So treat this as alpha quality folks...
What item in crate and jar contents are only determined when you open them, not determined as soon as they're generated in the level.
It worked like that in Spelunky Classic as well.
It's possible they use a separate seed.
For those who want Version 1.2 that doesn't have the watermark, PM me.
Most likely going to be buggy or feature-incomplete, since that's the old version.