Passcode Unsafe

I have ben using passcode in the filename as a password. The filename is like this Test223_300_C-1234567890-987654321-.jpeg (different number on the real phots). Yesterday I got a vomplanet the somone pit in 10% ti the password feaild and then gor some ranom photos froe a difrent gallery then the originat photi is supose to be in, I tride 20% as well and I got photos from 2 difrent gallerys. I close the page and all gallery's on that page. 

Is this some bug or something maybe I did wrong.

I am currently changing the side and gonna use CSV file to upload the passwords. Culd the same thing happen with thatt methed as well.

I can not replicate any issue with this. You would need to email me the photo file it is pulling up when entering 10% or 20%