If your drill diameter specification refers to finished (through plated) holes, 4 mils clearance means that the originally drilled holes are actually touching. Most PCB manufacturers will reject the design.
Regular design rules expect separated via pads for same net.
Why do you want to add two neighbor vias at the same track ? The purpose of the via is to change the layer on routing, and it was already made with the first one.
Why do you want to add two neighbor vias at the same track ? The purpose of the via is to change the layer on routing, and it was already made with the first one.
It could be for increased current capabilities. From his image, it looks like the two traces are going to ground. I often did this with high power traces.
It could be for increased current capabilities. From his image, it looks like the two traces are going to ground. I often did this with high power traces.
I also often spread some vias along the ground plane or over thin tracks carryng high currents changing the layer in a populated board, anyway even not considering a further pouring plane at the routing stage, it should be considered to enlarge the width of the above track. For the purpose of carrying ground current I would use a track thicker than the via external dimension. It seems to have enough space there.