Not only does the gif only have 2 flashes, but the caption of the gif and the article text differ. The caption says there are 2 flashes on the right, the article immediately under the caption says 2 on the left.
It does qualify the two-on-the-left version as "in traditional experiments", but yes, even then it's still not 100% clear if they are describing two different versions there on purpose or by accident.
