in the latest dev builds netbeans.conf contains definition of netbeans_default_options twice:
> netbeans_default_options="-J-client -J-Xss2m -J-Xms32m -J-XX:PermSize=32m -J-Dnetbeans.logger.console=true -J-ea -J-Dapple.laf.useScreenMenuBar=true -J-Dapple.awt.graphics.UseQuartz=true -J-Dsun.java2d.noddraw=true -J-Dsun.zip.disableMemoryMapping=true -J-Dplugin.manager.check.updates=false -J-Dsun.awt.disableMixing=true"
> # Note that default -Xmx and -XX:MaxPermSize are selected for you automatically.
> # You can find these values in var/log/messages.log file in your userdir.
> # The automatically selected value can be overridden by specifying -J-Xmx or
> # -J-XX:MaxPermSize= here or on the command line.
> #
> # If you specify the heap size explicitly, you may also want to enable
> # Concurrent Mark & Sweep garbage collector.
> # (see http://wiki.netbeans.org/FaqGCPauses)
> #
> netbeans_default_options="-J-client -J-Xss2m -J-Xms32m -J-XX:PermSize=32m -J-Dnetbeans.logger.console=true -J-ea -J-Dapple.laf.useScreenMenuBar=true -J-Dapple.awt.graphics.UseQuartz=true -J-Dsun.java2d.noddraw=true -J-Dsun.zip.disableMemoryMapping=true -J-Dplugin.manager.check.updates=false  -J-Dnetbeans.extbrowser.manual_chrome_plugin_install=yes"

maybe a result of an incorrect merge?
found in 201209140001