Dump her.

She's partially working against you in finding home, I don't see any reason for hesitation in getting rid of her.

Your agent owes fiduciary duties to you and that means due care and loyalty.  Due care is represented by the actions of a reasonable agent in the same or similar circumstances and loyalty means no self dealing.  Arguably, as I understand it from your narrative, these listings were on the MLS or some other type of website, available to all so your agent could simply say that their other client wanted to see these properties.  However, in the second circumstance where you have made an offer through your agent then her attempts to sabotage your offer by showing the property to another of her clients, if the client makes a  better offer than you made and gets the property,  then that may be an intentional interference with prospective economic advantage, by your agent.

If I were you I would call her supervising broker and explain the circumstances and request another agent or just dump her. 

 And, no this is not anyway for an agent to behave, unless she fully disclosed what she was going to you before she did in and you approved.

Of course all this is just my opinion.

If only you had a Real Estate Salespersons license you could argue for commission due since you were the procuring cause.

Step 1: Fire away. There are better agents out there. Why put up with the terrible ones?

Step 2: Put everything in writing with any evidence / emails / ect.

Step 3: Send to Broker of record with a CC to the California Department of Real Estate. This kind of nonsense should not be tolerated.

At minimum a call to you giving you a "last chance" to put an offer in should have been done. I say let the chips fall where they may.

Thanks for reading,

LoansbyJW

You are doing the research. Go directly to the listing agent. I cant begin to say how much of a better response I have gotten by doing this. They are much much more motivated if they are going to double end the deal, and they will put your offer on the top of the list.

If you don't have a Buyer's Agent contract with her then I would dump that agent in a heartbeat.  If you do have one isn't this a violation?

You are finding the listings?  You made an offer on one, and she knew what your offer is, and then she goes and shows it to an investor "after" your offer is in? This is ludicrous.