Recovered someone else's data from MY Sandisk sd card!

In 2015 I bought a Sandisk Ultra 64 GB micro sd card for my phone. I bought it from, a site that has daily deals.
A few weeks ago, on holiday, my phone suddenly didn’t recognize the sd card anymore.  Back home, I used the program Data Rescue 3 on my mac to try and recover what was on the sd card. 
To my surprise, the program recovered 40 GB of data (pictures and mp3s) that weren’t mine!! Almost 1,5 years worth of daily pictures and music from some other Belgian girl (I’m from Belgium too).
Does anybody have an explanation for this?? I bought the card as new from iBood.

i am not sure if is an authorized reseller. if not there is no telling where they got the cards. i would suggest contacting sandisk support directly so they could look into the issue for you.