They really should have the “double enter” issue built into the system, but there are user scripts for all this.
[Userscript]: Double-Check (Version 2.x) fixes the “double enter” issue and also will auto-proceed to the next answer if you get it right (via an optional setting). Of course, this script also let’s you undo wrong answers (very powerful, but dangerous), among other things. Pretty much all the features in this script are available individually in separate scripts, but I don’t remember what all the scripts are called.