What happens if you plug more than one charger in the new MacBook Pro (2016)?
The system will choose the power source that provides the most power, and it will not draw power from the others.
Apple has released a support article (and another one) describing this:


Your MacBook Pro draws power from only one power supply, even if more
than one is attached—so using multiple power supplies will not speed
up charging.

If you connect multiple power supplies to your MacBook
Pro, the one that provides the most power will be used, regardless of
the order in which you connected them.

You should not connect any
power supply that exceeds 100W, as it might damage your Mac.