Need advice on these diodes

I have found some zener diodes on a nanao chassis that have polarity in both directions. I am wondering if those specifically are some exception to the rule for some reason or another. Its not just the zener types, its a few others also that have polarity in both directions. So should I replace all of them? The suspect ones actually are around a board connector to another cable. I found another elsewhere, but most are there.

All zener diodes can run current forward and reverse bias. Reaching breakdown voltage of the zener puts it in a reverse bias state.

You can do a standard Resistance test and/or Voltage test to determine if they are good or shorted/open.

Your seeing the zener breakdown voltage in reverse polarity, depending solely on the type you can see .7V forward and 1V reverse. Zeners diodes when configured in reverse polarity are used to clamp voltages and as regulators in linear power supplies.