zinsco panel

This zinsco panel has two different color bus bars, is this normal for these panels?

This is a split-bus panel. The bus bars look the same to me, maybe a bit more oxidation on one side.

One looks CU and the other AL to me, just never seen that befor.

Its really hard to tell from the pictures, but I think I agree with Jeff. I think one has slightly oxidized more. (But the contrast in pictures is really hard sometimes.)

There were panels made with CU bus bars, and others made with AL, but I have never seen them mixed in the same panel unless it was a modification after the original installation.

In any case, this would not be a defect in itself.