The most likely reason you're getting extra milk from your other flange after using our flange is simply that you triggered another letdown (milk ejection).
There's normally have two or three letdowns with each feeding or pumping session. The milk flows strongly at first then dwindles down, but a few minutes later another letdown happens and the milk begins flowing stronger again.
Try leaving the silicone flange on for a few more minutes and see if the second letdown happens without changing flanges. If it doesn't or you're still having trouble, reach out to us and one of our inhouse lactation consultants will help.
Reviewed by Diana West, IBCLC
June 10, 2021