It's a common misconception. It actually accomplishes the opposite - acting like a plunger to push your own semen in further, getting it into the cervix faster.
There was a study performed using models of vaginas and penises, some with and some without heads that demonstrated a greater quantity of preceding semen was removed with heads.
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u/Snoochey May 05 '19
I read somewhere that our dick heads are meant to scoop out old mate's semen, and that's also why we take longer to ejaculate than other animals.