Yes this is doable, but I don't think you can do it in the text processor unfortunately.
edit: for what it's worth, this seems like a text processor bug so it'd be worth reporting it.
Here's how I did it in gamebook mode in the web editor:
1. Choose Page type --> Script
2. Add new script --> Variables --> Set a variable or attribute
3. Set variable random = expression GetRandomInt(0, 1)
4. Add new script --> Scripts --> If
5. If expression random = 0
6. Add new script --> Print
7. Print message First choice {img:
filename}
8. Add Else If
9. Else if expression random = 1
10. Add new script --> Print
11. Print message Second choice {img:
filename}
A couple of notes:
* You can choose Page type Script + text and do basically the same thing to combine this with static text.
* If you want to intertwine random text with static text you can have a series of Print scripts combined with a script like the above. Unfortunately more work than just using plain text with the text processor.
* The above in code view:
random = GetRandomInt(0, 1)
if (random = 0) {
msg ("First choice {img:lava canyon 004.jpg}")
}
else if (random = 1) {
msg ("Second choice {img:lava canyon 006.jpg}")
}