The question has knocked me out....

We have those contingencies in our MLS.  In our market, a Kick OUt is a clause in a contract that gets activated if you get a back up offer.  It is only found in home sale contingencies in our local contract.  If a buyer has a home to sell, and a back up offer comes in, seller would deliver notice to buyer that the "kick out" is in effect.  The buyer would have whatever amount of time the kick out period is to remove the contingency or the contract becomes void.

It is not a contingency to use just because you want back up offers.  It signals to buyer agents that their offer can boot out the contract you have.

IT SOUNDS LIKE the former gives the seller the option to notice buyer to remove all contingencies or cancel should a better offer come in.
The latter may have contingencies like inspection or financing, that a backup offer would have to wait for a fallout.
Not seeing your contract, I'd say you may need to refer your seller to a real estate attorney who can decipher which one fits your situation.

I think here it's called kick out clause. 

Talk to your broker. In each state the practice is different.

Are you referring to a "bump clause"... based on a contingency?

What is KO? Never heard of it

What is KO?  Not familiar with KO in PA.

Are we talking boxing??

You may want to consult with your Broker.

I'm not familiar with Knock contingency. Can you clarify what that means? 

Great answers for your question. 

Sounds like a clause that will have many meanings depending on where you are.

Great answers you got for your question.

We don't use that term so not sure what you are referring to.

Since I have been a member of AR, I have seen this term in other parts of the country, it's not used in my market area.    All real estate is local.   

Do you mean a Kick Out clause? A stipulation that performance needs to be within a specified time if another offer is received free of that contingency (e.g. sale of buyer's home). 

When the buyer has to sell their home to purchase this home. the offer should be written with contingent knock out.

I have never heard those terms before...they are probably specific to your state.

You should talk with your broker. I've noticed clauses available that we don't use.  I think your question is confusing the way you asked.  

This is an interesting question.

Try to use English properly and grammar is important in any business.