Sounds like there is a good loop hole to get out of your agreement but definitely check the dates prior to moving in a different direction. Procuring cause is what determines whether the agent is owed a commission on the properties you have seen. Unfortunately "procuring cause" in regards to real estate transactions is pretty grey terminology; It pretty much states: "A broker will be regarded as the "procuring cause" of a sale, so as to be entitled to commission, if his efforts are the foundation on which the negotiations resulting in a sale are begun. A cause originating a series of events which, without break in their continuity, result in accomplishment of prime objective of the employment of the broker who is producing a purchaser ready, willing, and able to buy real estate on the owner's terms." ... If you decide to buy one of the houses you simply saw with your old agent it would be pretty difficult for them to prove they had an unbroken series of events that lead to you buying that property and collect a commission. Your new agent should help you go over the "chain of events" and determine if there is any real worry and then be willing to handle any commission disputes between their firm and the old agents (take the weight off your shoulders).
Hope that helps! best of luck