Hi FF
Not too sure how Python works but I assume you have 2 blocks of 2 servos each block.
Also assume that it is OK to have the servos in each block to move in turn and you want to have the 2 blocks functioning at the same time.
I don’t know how good the actual multitasking is but the Pi Pico has dual core but from what I have read so far you seem to have tried this (i think that is what threading is all about). I will soon be diving into this further for another idea I have.
The only other way I can think of is have 2 micro devices.
Cheers Bob