As far as the 2x14awg romex test was concerned:
1. Take two 50 foot lengths of 14awg romex.
2. Take the two black hot leads of both cables and connect them to the same 15A/20A circuit breaker.
3. Take the two white neutral leads and connect to neutral bar in sub-panel.
4. Take the two bare ground leads and connect to ground bar in sub-panel.
5. Run the two 14awg romex cables to outlet.
6. Connect the two black hot leads to hot connection on outlet.
7. Connect the two white neutral leads to neutral connection on outlet.
8. Connect the two bare wire ground to outlet ground.
So, essentially, I am doubling the size of the wiring from circuit breaker to outlet. This is the same thing that happens inside larger power cords.
1. Take two 50 foot lengths of 14awg romex.
2. Take the two black hot leads of both cables and connect them to the same 15A/20A circuit breaker.
3. Take the two white neutral leads and connect to neutral bar in sub-panel.
4. Take the two bare ground leads and connect to ground bar in sub-panel.
5. Run the two 14awg romex cables to outlet.
6. Connect the two black hot leads to hot connection on outlet.
7. Connect the two white neutral leads to neutral connection on outlet.
8. Connect the two bare wire ground to outlet ground.
So, essentially, I am doubling the size of the wiring from circuit breaker to outlet. This is the same thing that happens inside larger power cords.