Double Triodes in parallel

[abbey road d enfer]

I don't think it would impair life expectancy, the question would be if there's any performance change due to half the expected plate size, or from the other angle, double the cathode emission.

I don't understand your question; the two halves in a dual triode are isolated from each other, almost as much as if they were in two separate bottles.

 

[emrr]

The emitted electrons exist in the same vacuum, do they not? 

 

[abbey road d enfer]

The emitted electrons exist in the same vacuum, do they not?

Just like we both live in the same world, but don't actually interfere much.

 

[emrr]

Just like we both live in the same world, but don't actually interfere much.

They are designed to not interfere much when used as planned, the question is what if anything the extra emission does when it's attracting plate element is not powered.  It would seem to be attracted to the opposing plate, to what end?  Possibly none.  Could depend on the type and usage.