A new IC (IC 2) whose client list I imported included a client who already existed in our system belonging to another IC (IC 1). The system matched via the email and updated the info for the client as IC 1's client - leaving the cleint assigned to IC 1 rather than switching him to IC 2. Ultimately, it's good in this instance that the client remained assigned to IC 1, but all of the info IC 1 had in the profile was overwritten by the info IC 2 had in their data.

The client uploader within TS only shows you a preview of the first 25 names so I'm sure that the system caught that the client's email already existed, but IC 2 had thousands of clients and that client wasn't in the first 25 rows. As a result, I couldn't see the system flag it and I didn't have a chance to fix it.