If you are booked through one airline but the flight is operated by another, then sometimes you get two PNR and records in ba.com. Happens to me regularly when flying LHR-HEL-LHR using a BA ticket but AY metal.

It's possible that the TA has made the change but the echo-PNR has not updated (again, happens to me regularly on LHR-HEL-LHR). Maybe there was no change fee and the TA did not properly listen to your "just interested, not committing"?