Q: ipod 5 without back camera

That would be a question for your seller and what their return policy is I'm afraid.

If I'm remembering right the 16 gig had no camera, the 32 and above do. (that or the 8 gig, something like that)

It's possible that it was a simple mistake. Grabbed the wrong thing and scanned the other twice by mistake.

The device (5G iPod touch) was initially only sold in 32GB and 64GB models. The first 16 GB model, introduced on May 30, 2013, was only available in one color and lacks the rear iSight camera and the iPod Touch Loop that is included in the 32 GB models.[4] On June 26, 2014, it was replaced with a new 16GB model that no longer omits the rear camera and full range of color options. The pricing for the iPod Touch had also changed. The 16GB model is $199 instead of $229, the 32 GB model is $249 instead of $299, and the 64 GB model is $299 instead of $399.[5]

Above from:

https://en.wikipedia.org/wiki/IPod_Touch_(5th_generation)

You have to resolve it with the seller. It is not Apple's problem.