One would trigger before the other, so if the 2nd has too low HP, it will die.
Otherwise, yes, both would constantly gain attack.
I'm not too concerned about this being too strong. Compare it to 2 forest spirit.
This will require at least 4 creatures, and instantly costs 10 quanta-
The forest spirits continually drain 2 quanta each turn.
It will take at least 5 turns before axis of the machine outvalues forest spirit.
Gravity already has high HP, so with this strategy, acceleration/overdrive is probably better.