One only has to Google: Walmart Music & Censorship to find hundreds of citations.
I decided to explore a bit more deeply and found that a free-lance A&R man had tried to convince the retail monlith to conceal the real CDs in other album covers. Here are a few of the results of my inquiry.
*

*
*

*
*

*
*

*
*

*
*

*
*

*
*
Images: (LP covers) porktornado.diaryland.com; (small covers) all over net