Can there be a test between identical actions for the period of time between them. Let's say the fastest someone can double click a key is every 100 ms. (This should be tested to find out what a reasonable minimum period is.) If the previous occurrance of an action, say, turn-left, was executed less than 100 ms earlier, then a player could warned or kicked. It could work like spam protection. Warning them first, and if it happens too much within a certain time period, it could kick them. This would even allow a double binder to use it occasionally to get out of a sticky situation, but would prevent them from repeatedly double binding to cause server lag. This will not prevent people from using double key binding as additional key options.
Or maybe if they double key bind repeatedly, their cycle delay could increase each time. (It would fall again with time) It would be pretty hard to lag the server if your cycle delay increased to a whole second.

Thoughts? Is this possible? Would it be difficult to code? Would it be a practical solution?