Do two stage common emitter current amplifiers add or multiply?
If you mean something like below, then the currents add:



As Alfred mentions, this is not known as a "two stage CE amplifier" though.
With BJTs, the emitter resistors are needed to prevent thermal runaway. This is caused by the fact that as a BJT gets hotter it passes more current. The emitter resistor provides some negative feedback (higher current = more voltage across resistor = lower Vbe to stop runaway) but wastes power.
FETs don't have this problem and can be connected directly, so are better for parallel operation.