To remove duplicate items in fzf prompt, add the following lines into ~/.zshrc:
setopt EXTENDED_HISTORY
setopt HIST_EXPIRE_DUPS_FIRST
setopt HIST_IGNORE_DUPS
setopt HIST_IGNORE_ALL_DUPS
setopt HIST_IGNORE_SPACE
setopt HIST_FIND_NO_DUPS
setopt HIST_SAVE_NO_DUPS
setopt HIST_BEEP
Ref:
Preventing duplicate lines in the history
https://github.com/mattjj/my-oh-my-zsh/blob/master/history.zsh