The diagram shows 2 wires connected to the same pin

Breadboards are built of strips and columns, as you can read here. While it is not possible to connect two wires to the same pin, sometimes, there are glitches in our generator that cause it to connect two wires to the same pin. In this case, you can place one of the wires next to the other, but make sure it is in the same column or strip, depending on the region of the breadboard you are working in: If it occurs in the bus strip, you need to make sure you are in the same strip (ground or power), if it occurs in one of the columns, make sure to stay on the same column.

Hi, thank you yoav for this helpful answer. I have another question related to this one. In a case where the diagram show to wires in the same pin on the Arduino UNO (In my case, 4 wires in the 2 gnd pins), what would be the best solution ? Is there some Y adaptator that existe?

Hey if this is happening with gnd pins, then, as Yoav wrote, you need to connect them to the same bus strip. If the issue occurs on the columns - make sure to put all the pins in the same column. I hope this is clear. If not, send a screenshot or a link to the reply and I will give a more elaborate answer.

Actually, the issue is happening on the arduino board, not on the breadboard. Here is a picture of the diagram: