Use HISTIGNORE in bash
Don't you find it annoying when you have been using the same command in bash a few times in a row, and then you scroll through the history to a previous command only having to go through many duplicates of the command you just used.
For this use bash's HISTIGNORE variable, set in in your ~/.bashrc file.
Will mean you will not have duplicates in your bash history, but you can use other varables too, say you don't want the commands beggining with c to be put in the history.
An example of this together with not having duplicates: