Is it normal to have duplicate JVMs or JDKs in a MacBook? I just bought my first MacBook Pro a week ago and this morning, I installed the Java for OS X 2012-004 Developer Package at http://connect.apple.com. Right now, I'm encountering a bunch of weird errors in my code and I wonder if what I just did is to blame, since this machine came with Java built in.

So when I click on the .jdk file in the Developer Package, this is what I see:



Is that normal? I think they are exact duplicates of each other and might be causing the bugs I'm dealing with right now. I'm not sure if there were four or only two entries before. How do I delete the other JDK if it's a duplicate?
That is normal but they are not exact duplicates. To test I just installed the 
developer package that you mentioned. This added the two Java SE6 non system lines.

So I think the four packages you see are split by 32 or 64 bit and whether they are the JDK or the JRE needed to just run java and installed when you are asked to run a Java program or web plugin.

As to the 'wierd' errors best to show those and the code in a question on Stack Overflow.