PCB modified during fab


I have send 2 PCB to be manufactured, and I have been surprised when I have received them because on both of them a copper has been added on both sides.

Files I had sent did have copper on bottom only for the first PCB, and no copper at all for the second PCB.

Is this normal ?
I believed that files where not modified during fab process.


I just wanted to add something found into the FAQ:

> **5. Do all the boards have the Fritzing logo on it?**
> No, your boards will completely look like you designed them! If you 
> like, you can put any logo or illustration on it using the "logo" item 
> from the core parts library. Please notice, that the Silkscreen print is
>  black/white without grayscale. You can find the Fritzing logo there, 
> and those of OSHW and OHANDA, but you can also load your own svg-file.