Cover Similarities

I've begun to notice an interesting phenomenon in the publishing world.  It's become more noticeable since I started blogging and more and more books that I would never know about come to to my attention.  It's not really bothersome like say the whitewashing of covers, more along the lines of annoying.  What am I talking about?  The use of the same cover over and over, only changed in small little ways.  I'm curious as to how this process works.  Do publishing companies think that because books are different genre's or different publication years, that we won't notice?  Is there a collection of stock photo's that all publishers have access too?  Take the following for example...

 Now, Tantalize and Ivy are bother young adult.  But, different publication companies and different years.   Goodreads has a few different covers for Ivy (but I wonder if its still the same model).  The Homeplace was the first of these novels to come out.

How about these two:

  

What I thought was amusing about these two was that the title are so similar.  Both of these will be (or have been) released in 2010, but once again different publishing companies.

 Now, I know this is just the tip of the iceburg.  I've seen lots of others that look similar and even some that are hard to tell if it's the same cover.  These were ones that have been sticking out in my mind lately.  So what do you think about this?  Does it bother you or do you not really care?