Something very strange is happening!

So I have this URL set up:

FROM URL: /index.php/tefl-resources/index.php/ESL_Bingo
TO URL: /index.php/tefl-resources/tefl-lesson-plans-activities-ideas/35-esl-bingo
Case sensitive OFF
Request Only OFF
Decode URL OFF

And it works fine.

However, I have this setup:

FROM URL: /index.php/tefl-resources/index.php/Writing_Prompts
TO URL: /index.php/tefl-resources/tefl-lesson-plans-activities-ideas/35-esl-bingo
Case sensitive OFF
Request Only OFF
Decode URL OFF

And it doesn't work! It goes instead to /index.php/tefl-resources/

The only difference between the two is the very ending of the second FROM URL.

It seems - although I could be wrong - that this URL is somehow being intercepted before reaching ReDJ. Is that possible? I do not have the plugin for the standard J2.5 redirect turned on.