[morzh]

Well, I do not know of this particular radio.
Let's just say you have a battery. The battery can output 1.5A at 1.5V. That is, it can see 1 Ohm load.
Then you parallel two of these. They will do exactly the same, output 0.75A each so together they output 1.5A.
But, each one being capable of 1.5A, you could reduce the load to 0.5 Ohm so the current now is 3A.
But each one outputs 1.5A which is equivalent of each seeing 1 Ohm load.

Same here. If the single pushpull wants to see 14K it means that two in parallel, in order to see 14K each, need to see 7K full load.

Now, you have to see what the transformer is.
This coupled with your load determines what the tubes will see at the primary.
When they say "14K" it means it could be less. But then the power transfer won't be optimal.