Why does the Antifa flag mimic the nazi flag?

I was doing some reading this morning, and it hit me.  How much the Antifa flag looks like the Nazi flag.

The caption also says it all.  Everyone knows I am a supporter of protests, but there is no need to be doing things like throwing bottles of urine at police.  If that isn’t bad enough, mainstream media doesn’t condemn the attack.

On the flipside, if the police attacked the urine throwing protesters, the police would be criticized.  Can someone please help me understand.