I have seen this ‘error’ on many of my plots as well.
The error is caused by different pen height when installing the second pen.
If the pen is just a tiny fraction off compared to the first one this will be the result.
I use a bent paper clip and a point source light (LED lamp) to align the pen, see picture.
When the shadows meet I have the correct height. (I align the shadows by moving the lamp before starting the first plot – but after I “Enable Motors” in the “manual” tab of the eggbot dialogue.) For this procedure to work the pens have to be the same type as a difference in diameter will throw the “calibration” off. It’s also important not to move the light and/or eggbot during the plot. The egg have to be in the same position as well as most eggs are not perfectly round. (My eggs are ceramic eggs bought at Hobby Lobby. They have the same “perfect imperfections” as “real” eggs.)
By the way, how do you get your images to show in the posts?