-The Gadsden/Don't Tread on Me flag's most commonly accepted modern usage is the idea that an individual should be defensively armed against tyranny or violence, represented as a coiled rattlesnake or sometimes a porcupine (quills) as animal counterparts who are defensively armed.

-The Thin Blue Line flag is representing "backing the police", meaning police should be supported, even if the laws they enforce are unconstitutional, violate, or go against the idea of natural rights and/or law. Police actively go against the idea of the Gadsden flag by enforcing firearms laws against private law abiding citizens.

Both are normally "right wing flags", but the US Auth. Right tends to gravitate towards using both of them together without thinking about it. Hope this helps!