Therapists do consult with each other all the time. But they are supposed to leave names out.

How do you know he is also your therapist's therapist? Did your first therapist refer you to him? If so, that is another way the information could have leaked - some therapists call the party they made a referral to and outline why they made the referral.

Were you planning to switch to the second therapist? Why did you email him?