Is this how Amazon Swords reproduce?

they do it to reproduce. making sure they have everything they need to survive really helps. try some root tabs under yours.

I've had two plants one on each side of a 125 w/384w of PC lights, pressurized CO2 and modified EI dosing. For three years neither every threw a runner although they were almost 2' in each direction. I had an equipment malfunction and for about 3 months there was no CO2 injection and they exploded with runners everywhere. That was about a year ago. I removed the runners (the tank was literally overflowing with plants), corrected the CO2 issue and haven't seen another runner since.
 
AquariaCentral.com