Multilayer Trace Distributiond

I’m considering a trace that needs to handle a current of 20 amps with a temperature rise of 20°C on 1oz copper. According to an online calculator, this requires a trace width of 12.60mm.
My query is whether it’s feasible to split this width evenly between the bottom and top layers (6.30mm each) and then connect these layers using vias. If this method is viable, are there any special considerations or potential issues to be aware of? Any insights or advice on this approach would be appreciated.

If your using multiple vias then I wouldn’t expect problems. I might add just a tiny bit to the width if your dividing as a safety factor, but running multiple traces on different layers is a time-honored workaround. Done it myself.

Multiple parallel layers is a good idea.

Keep in mind that too many vias (think holes in copper) along the entire copper current path can increase overall resistance of each layer and increase heat buildup of high current paths. I am talking about adding excessive via counts. Only add as many vias as required at each end of the path to allow half of the proposed current to travel to other parallel layer.