Should I replace just the burnt exhaust valves?

.. I have 3 cylinders with low compression.

Yadda yadda, I got the head off and tested the valves and i have a few exhaust valves that leak bad. See vid here https://youtu.be/aQji8LHWoiI

In the pics below I have cylinder 1 exhaust valves out.
The one that leaks is like a oval shaped compared to its sister exhaust valve...I'm assuming this is a "burnt" valve.. although I'm new to this. I checked the valve clearances before I took the cams off and all exhaust valves were tight.. like 0.000" clearance.. actually 3 of the 8 were 0.006 which is still out of spec and way tight. Spec is 0.010 to 0.014"

anyway you can see the lip in the pic when I put them end to end. ... and in the side by side pic the height difference is visible too

Is it common to just replace them all at the same time? Or can I replace only the 3 that are obviously not round?