Tā piēle piězuǐ.
His lips curled in a contemptuous smile (or a sneer).
I'm puzzled as to why the pinyin on the first 撇 is given as piē (1st tone) above. My understanding is that this is an example of verb reduplication, so the two 撇s are the same, in which case I would expect their pronunciation to be the same. So...
Question: Is the pinyin for 他撇了撇嘴 actually "tā piē le piězuǐ" (as given by Pleco)? And if so, why are the two 撇s pronounced differently?