> Bad example: Java actually has many VMs available for it: Oracle, OpenJDK, Zing, and IBM come to mind. I'm unsure if Java has multiple compilers, but its quite possible.

It does have multiple compilers for java, at least javac and ecj (eclipse compiler for java) http://blog.deepakazad.com/2010/05/ecj-eclipse-java-compiler...

And if you consider groovy and scala and kotlin it has many more compilers.