A puzzle for the reader

Here is a puzzle for the reader.

Consider this 2004 study by the same group as the previous posts: "Chronic haloperidol promotes corticostriatal long-term potentiation by targeting dopamine D2L receptors.", Journal of Neuroscience, 2004, 24: 8214-8222.

This study was corrected few months later in an Erratum (Journal of Neuroscience, 2005. 25: 1034-1035). The Erratum replaces five of the paper's six figures (only Figure 1 is spared). According to the Erratum, the figures needed to be replaced because of "incorrect control data points [...] corresponding to pretetanus values of the LTP experiments."

This might be an incomplete explanation for the replacement of the figures. Indeed, looking back at the original Figure 3C (which appears below), can the reader spot a remarkable coincidence? Notice that these traces are not "control data points".