One MANILA applicant got Medical request and He/She is post June 26, 2010 applicant, so probably your Visa Office lady correctly advised you but I would rather request you wait and watch/get further confirmation from you visa office regarding the same before withdrawing any of the two applications.
I have two applications. one is pre 626. The course shows at the bottom. The other is post 626. It was sent to the CIO on Oct. 4. I got my PER by email on Feb. 7. The VO asked me to withdraw one and said the post 626 applicants get priority. I am still hesitating....